Multiple input multiple output (mimo) setup in millimeter wave (mmw) wlan systems

ABSTRACT

An AP/PCP may perform user selection/pairing/grouping based on a measurement of an analog transmission (e.g., signal to noise ratio (SNR) or signal to interference plus noise ratio (SINR)). The SNRs may be used, for example by the station, to determine best beams and/or beam pairs and/or worst beams and/or beam pairs. A station may feed back the best few beams and/or beam pairs for a Tx and Rx virtual antenna pair. A station may feed back the worst few beams for the Tx and Rx virtual antenna pair. The AP/PCP may receive the indication(s) and/or use the indication(s) to group the stations.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the benefit of U.S. Provisional PatentApplication No. 62/365,141, filed Jul. 21, 2016, the contents of whichis incorporated by reference.

BACKGROUND

A Wireless Local Area Network (WLAN) may have multiple modes ofoperation, such as an Infrastructure Basic Service Set (BSS) mode and anIndependent BSS (IBSS) mode. A WLAN in Infrastructure BSS mode may havean Access Point (AP) for the BSS. One or more wireless transmit receiveunits (WTRUs), e.g., stations (STAs), may be associated with an AP. AnAP may have access or an interface to a Distribution System (DS) orother type of wired/wireless network that carries traffic in and out ofa BSS. Traffic to STAs that originates from outside a BSS may arrivethrough an AP, which may deliver the traffic to the STAs. In certainWLAN systems, STA to STA communication may take place. In certain WLANsystems an AP may act in the role of a STA. Beamforming may be used byWLAN devices. Current beamforming techniques may be limited.

SUMMARY

Systems, methods, and instrumentalities are disclosed for setting up amultiple input multiple output (MIMO) frame for MIMO transmission.

An AP/PCP may perform user selection/pairing/grouping based on ameasurement of an analog transmission (e.g., signal to noise ratio (SNR)or signal to interference plus noise ratio SINR). SNR/SINRs may beacquired by analog beam training. During analog beam training, the APmay send from a virtual antenna of the AP one or more analogtransmissions. The virtual antenna of the AP may transmit via one ormore analog beams (e.g., a transmission per beam). A station may receivevia a virtual antenna of the station the one or more analogtransmissions. The virtual antenna of the station may receive the one ormore analog transmissions via one or more analog beams. For example, abeam of a virtual antenna of the station may receive some or all analogtransmissions from the AP. An analog transmission of the one or moreanalog transmissions may be communicated from a beam of a virtualantenna of the AP to a beam of a virtual antenna of the station. Thebeam of the virtual antenna of the AP and the beam of the virtualantenna of the station may form a TX and RX beam pair. The beam of thevirtual antenna of the AP may be the TX beam in the beam pair. The beamof the virtual antenna of the station may be the RX beam in the beampair. Different TX and RX beam pairs may be associated with SNRs. SNRsmay be measured, for example by the station, based on the analogtransmission communicated between the TX and RX beam pair.

The SNRs may be used, for example by the station, to determine bestbeams and/or beam pairs and/or worst beams and/or beam pairs. In anexample, an SNR threshold may be used for characterizing the beamsand/or beam pairs. The beams and/or beam pairs associated with an SNRthat is greater or equal to the SNR threshold may be characterized asbest beams and/or beam pairs. The beams and/or beam pairs associatedwith an SNR that is less than the SNR threshold may be characterized asworst beams and/or beam pairs.

A station may feed back the best few beams and/or beam pairs for a Txand Rx virtual antenna pair. A station may feed back the worst few beamsfor the Tx and Rx virtual antenna pair. For example, the station mayfeed back the best and/or the worst few beams to the AP/PCP via anindication(s). The indication(s) may include a MU MIMO set up frame(s).

The AP/PCP may receive the indication(s) and/or use the indication(s) togroup the stations. For example, the AP/PCP may receive, from onestation, an indication of the best beam and/or the worst beam for thestation. The AP/PCP may receive, from another station, an indication ofthe best beam an/or the worst beam for the other station. The AP/PCP maydetermine based on one or more of the indications for multiple stationsthat the best beam for one station may be among the worst beams foranother station. The AP/PCP may determine to group the two stations fortransmissions (e.g., DL MU-MIMO transmissions). The AP/PCP may indicateto both stations about the grouping. In the example, the AP/PCP mayindicate to both stations about the allocation of the respective beam/RFchain/virtual antenna allocation to the respective station.

BRIEF DESCRIPTION OF THE DRAWINGS

A more detailed understanding of the embodiments disclosed herein may behad from the following description, given by way of example inconjunction with the accompanying drawings.

FIG. 1 is an exemplary sector level sweep (SLS) training.

FIG. 2 is an exemplary sector sweep (SSW) frame format.

FIG. 3 is an exemplary SSW field in a SSW frame.

FIG. 4 is an exemplary SSW feedback field in a SSW frame when nottransmitted as part of an ISS.

FIG. 5 is an exemplary SSW feedback field in a SSW frame whentransmitted as part of an ISS.

FIG. 6 is an exemplary physical Layer convergence procedure (PLCP)protocol data unit PPDU which carries beam refinement protocol (BRP)frame and training (TRN) fields.

FIG. 7 is an exemplary digital multimedia broadcasting (DMB) PPDUformat.

FIG. 8 is an exemplary enhanced directional multi-gigabit (EDMG) PPDUformat.

FIG. 9 illustrates an example diagram of MU-MIMO analog beam trainingselection.

FIG. 10A illustrates an exemplary multi-user (MU)-MIMO setupimplementation.

FIG. 10B illustrates an exemplary implementation for partialtransmission failure scheme 1.

FIG. 10C illustrates an exemplary implementation for partialtransmission failure scheme 2.

FIG. 11 illustrates an exemplary single user SU-MIMO setupimplementation.

FIG. 12 illustrates an exemplary MIMO setup implementation withbaseband/digital beamforming (BF)/MIMO training.

FIG. 13A illustrates Linear shift techniques for avoiding unintentionalbeamforming.

FIG. 13B illustrates techniques for avoiding unintentional beamformingblock-based shift which include some or all legacy fields.

FIG. 13C illustrates techniques for avoiding unintentional beamformingblock-based shift considering the subfields and their purposes.

FIG. 14 illustrates channel estimation operation in 802.11ad withchannel estimation field (CEF). CEF includes Golay sequence denoted asGa128 and Gb128.

FIG. 15A illustrates circularly shifted CEFs for two streams.

FIG. 15B illustrates circularly shifted CEFs for two streams andauto/cross correlation results.

FIG. 16A illustrates exemplary wireless local area network (WLAN)devices.

FIG. 16B is a diagram of an example communications system in which oneor more disclosed features may be implemented.

FIG. 16C depicts an exemplary wireless transmit/receive unit, WTRU.

DETAILED DESCRIPTION

A detailed description of illustrative embodiments may now be describedwith reference to the various Figures. Although this descriptionprovides a detailed example of possible implementations, it should benoted that the details are intended to be exemplary and in no way limitthe scope of the examples described herein.

A Wireless Local Area Network (WLAN) may have multiple modes ofoperation, such as an Infrastructure Basic Service Set (BSS) mode and anIndependent BSS (IBSS) mode. A WLAN in BSS mode may have an Access Point(AP/PCP) for the BSS. One or more stations (STAs) may be associated withan AP/PCP. An AP/PCP may have access or an interface to a DistributionSystem (DS) or another type of wired/wireless network that carriestraffic in and out of a BSS. Traffic to STAs that originates fromoutside a BSS may arrive through an AP/PCP, which may deliver thetraffic to the STAs. Traffic originating from STAs to destinationsoutside a BSS may be sent to an AP/PCP, which may deliver the traffic tothe respective destinations. Traffic between STAs within a BSS may besent through an AP/PCP, e.g., from a source STA to the AP/PCP and fromthe AP/PCP to the destination STA. Traffic between STAs within a BSS maybe peer-to-peer traffic. Peer-to-peer traffic may be sent directlybetween the source and destination STAs, for example, with a direct linksetup (DLS) using an 802.11e DLS or an 802.11z tunneled DLS (TDLS). AWLAN in IBSS mode may not have an AP/PCP, and/or STAs may communicatedirectly with each other. An IBSS mode of communication may be referredto as an “ad-hoc” mode of communication.

An AP/PCP may transmit a beacon on a fixed channel (e.g., the primarychannel), for example, in an 802.11ac infrastructure mode of operation.A channel may be, for example, 20 MHz wide. A channel may be anoperating channel of the BSS. A channel may be used by the STAs, forexample, to establish a connection with an AP/PCP. A channel accessmechanism in an 802.11 system is Carrier Sense Multiple Access withCollision Avoidance (CSMA/CA). A STA, including an AP/PCP, may sense aprimary channel, for example, in a CSMA/CA mode of operation. A STA mayback off, for example, when a channel is detected to be busy so that a(e.g., only one) STA may transmit at a time in a given BSS.

High Throughput (HT) STAs may use, for example, a 40 MHz wide channelfor communication, e.g., in 802.11n. A primary 20 MHz channel may becombined with an adjacent 20 MHz channel to form a 40 MHz widecontiguous channel.

Very High Throughput (VHT) STAs may support, for example, 20 MHz, 40MHz, 80 MHz, and 160 MHz wide channels, e.g., in 802.11ac. 40 MHz and 80MHz channels may be formed, for example, by combining contiguous 20 MHzchannels. A 160 MHz channel may be formed, for example by combiningeight contiguous 20 MHz channels or by combining two non-contiguous 80MHz channels, which may be referred to as an 80+80 configuration. An80+80 configuration may be passed through a segment parser that dividesdata into two streams, for example, after channel encoding. IFFT andtime domain processing may be performed, for example, on a (e.g., each)stream separately. Streams may be mapped onto two channels. Data may betransmitted on the two channels. A receiver may reverse a transmittermechanism. A receiver may recombine data transmitted on multiplechannels. Recombined data may be sent to the Media Access Control (MAC).

Sub 1 GHz (e.g., MHz) modes of operation may be supported, for example,by 802.11af 802.11ah. Channel operating bandwidths and carriers may bereduced, for example, relative to bandwidths and carriers used in802.11n and 802.11ac. 802.11af may support 5 MHz, 10 MHz, and 20 MHzbandwidths in a TV White Space (TVWS) spectrum. 802.11ah may support 1MHz, 2 MHz, 4 MHz, 8 MHz, and 16 MHz bandwidths in non-TVWS spectrum. Anexample of a use case for 802.11ah may be support for Meter Type Control(MTC) devices in a macro coverage area. MTC devices may have limitedcapabilities (e.g., limited bandwidths) and may be designed to have avery long battery life.

WLAN systems (e.g., 802.11n, 802.11ac, 802.11af, and 802.11ah systems)may support multiple channels and channel widths, such as a channeldesignated as a primary channel. A primary channel may, for example,have a bandwidth equal to the largest common operating bandwidthsupported by STAs in a BSS. Bandwidth of a primary channel may belimited by a STA that supports the smallest bandwidth operating mode. Inan example of 802.11ah, a primary channel may be 1 MHz wide, forexample, if there are one or more STAs (e.g., MTC type devices) thatsupport a 1 MHz mode while an AP/PCP and other STAs may support a 2 MHz,4 MHz, 8 MHz, 16 MHz, or other channel bandwidth operating modes.Carrier sensing and NAV settings may depend on the status of a primarychannel. As an example, some or all available frequency bands may beconsidered busy and remain idle despite being available, for example,when a primary channel has a busy status due to a STA that supports a 1MHz operation mode transmitting to an AP/PCP on the primary channel.

Available frequency bands may vary between different regions. As anexample, in the United States, available frequency bands used by802.11ah may be 902 MHz to 928 MHz. As another example, in Korea,available frequency bands may be 917.5 MHz to 923.5 MHz. As anotherexample, in Japan, available frequency bands may be 916.5 MHz to 927.5MHz. The total bandwidth available for 802.11ah may be 6 MHz to 26 MHzdepending on the country code.

802.11ac may support downlink Multi-User MIMO (MU-MIMO) transmission tomultiple STAs in the same symbol's time frame, e.g. during a downlinkOrthogonal frequency-division multiplexing (OFDM) symbol. MU-MIMOtransmission may improve spectral efficiency. 802.11ah may supportdownlink MU-MIMO. Downlink MU-MIMO may use the same symbol timing tomultiple STAs and the waveform transmissions to the multiple STAs maynot interfere with each other. One or more STAs in MU-MIMO transmissionwith an AP/PCP may use the same channel or band, which may limit theoperating bandwidth to a selected channel width (e.g., the smallestchannel bandwidth that is supported by the one or more STAs in MU-MIMOtransmission with the AP/PCP).

802.11ad is an amendment to the WLAN standard, which specifies themedium access control (MAC) and physical (PHY) layers for very highthroughput (VHT) in the 60 GHz band. 802.11ad may support data rates upto 7 Gbits/s. 802.11ad may support three different modulation modes.802.11ad may support control of PHY with single carrier and spreadspectrum. 802.11ad may support single carrier. PHY. 802.11ad may supportOFDM PHY. 802.11ad may use 60 GHz unlicensed band, which may availableglobally. At 60 GHz, the wavelength may be 5 mm, which may make compactand competitive antenna or antenna arrays possible. A compact andcompetitive antenna may create narrow radio frequency (RF) beams attransmitter and receiver, which may effectively increase the coveragerange and/or reduce the interference.

The frame structure of 802.11ad may facilitate beamforming training(e.g., discovery and tracking). The beamforming (BF) training protocolmay include two or more components: a sector level sweep (SLS), a beamrefinement protocol (BRP), and/or the like. The SLS may be used fortransmitting beamforming training. The BRP may enable receivebeamforming training and/or iterative refinement of both the transmitand receive beams.

MIMO transmissions, including both SU-MIMO and MU-MIMO, may not besupported by 802.11ad.

FIG. 1 illustrates an exemplary sector level sweep (SLS) training. SLStraining may be performed using a Beacon frame and/or a sector sweep(SSW) frame. When a Beacon frame is utilized, an AP/PCP may repeat theBeacon frame with multiple beams/sectors within a (e.g., each) Beaconinterval (BI). For example, an AP/PCP may repeat the Beacon frame in theSS frame 102 and the SS frame 106. Multiple STAs may perform BF trainingsimultaneously. For example, a STA may respond via frame 104, andanother STA may respond via frame 108. An AP/PCP may not sweep all thesectors/beams within one BI, for example, due to the size of the Beaconframe. A STA may need to wait multiple BIs to complete ISS training, andlatency may be an issue. A SSW frame may be utilized for point-to-pointBF training. A SSW frame may be transmitted using control PHY.

FIG. 2 illustrates an exemplary SSW frame format. The SSW frame mayinclude one or more frame control 202 (2 octets), 204 duration (2octets), RA 206 (6 octets), TA 208 (6 octets), SSW 210 (3 octets), SSWfeedback 212 (3 octets), or FCS 214 (4 octets).

FIG. 3 illustrates an exemplary SSW field in a SSW frame. The SSW framemay include fields or subfields of one or more direction 302 (1 bits),CDOWN 304 (9 bits), Sector ID 306 (6 bits), DMG Antenna ID 308 (2 bits),or RXSS Length 310 (6 bits).

FIG. 4 illustrates an exemplary SSW feedback field in a SSW frame whentransmitted as part of an ISS. A SSW feedback field in a SSW frame mayinclude fields and subfields of one or more total sections in ISS 402 (9bits), number of RX DMG antennas 404 (2bits), reserved 406 (5 bits),poll required 408 (1 bit), and reserved 410 (7 bits).

FIG. 5 illustrates an exemplary SSW feedback field in a SSW frame whennot transmitted as part of an initiator sector sweep (e.g., ISS). TheSSW feedback field may include fields and subfields of one or moresector select 502 (6 bits), DMG Antenna Select 504 (2 bits), SNR Report506 (8 bits), Poll required 508 (1 bit), or reserved 510 (7 bits).

Beam refinement may enable a STA to improve the STA's antennaconfiguration (e.g., or antenna weight vectors) for transmission and/orreception. Beam refinement may include using BRP packets to train thereceiver and/or transmitter antenna. There may be two types ofbeamforming refinement protocol (BRP) packets: BRP-receiver (RX) packetsand BRP-transmitter (TX) packets. FIG. 6 is an exemplary Physical Layerconvergence procedure (PLCP) protocol data unit (PPDU) which carries aBRP frame and training (TRN) fields. A BRP packet 602 may be carried bya directional multi-gigabit (DMG) PPDU, for example, and may be followedby a training field 604 that includes an automatic gain control (AGC)field 606. The BRP packet 602 carried by a DMG PPDU may be followed by atransmitter or receiver training field 608 as shown in FIG. 6

A value of N, as shown in FIG. 6, may be the Training Length given inthe header filed, which may indicate that the AGC has 4N subfields andthat the TRN-receiver/transmitter (R/T) field has 5N subfields. Thechannel estimation (CE) subfield 612 may be the same as the one in thepreamble (e.g., described herein). The subfields in the beam trainingfield 604 may be transmitted using rotated π/2− Binary Phase ShiftKeying (BPSK) modulation.

A BRP MAC frame may be an Action No ACK frame that includes one or moreof the following fields: Category, Unprotected DMG Action, Dialog Token,BRP Request field, DMG Beam Refinement element, or Channel MeasurementFeedback element 1 . . . Channel Measurement Feedback element k.

802.11ad may support four PHYs, including single carrier (SC) PHY, OFDMPHY, Control PHY, and low power SC PHY. The PHYs may share the samepacket structure though the detailed designs for each field may bedifferent. FIG. 7 is an exemplary digital multimedia broadcasting (DMB)PPDU format. The DMB PPDU format may include short training field 702,CE 704, header 706, data 708, and TRN-R/T subfields 710.

Task Group ay (TGay) may introduce modifications to both the IEEE 802.11physical layers (PHY) and the IEEE 802.11 medium access control layer(MAC) that enables at least one mode of operation capable of supportinga maximum throughput of at least 20 gigabits per second (e.g., measuredat the MAC data service access point), while maintaining or improvingthe power efficiency per station. TGay may introduce support foroperations on license-exempt bands above 45 GHz while ensuring backwardcompatibility and coexistence with legacy directional multi-gigabitstations (e.g., as defined by IEEE 802.11ad-2012 amendment) operating inthe same band.

802.11ay may include mobility and/or outdoor support. 802.11ay mayoperate in the same band as legacy standards and may include support forbackward compatibility and coexistence with legacies in the same band.802.11ay may include MIMO and channel bonding. In order to support MIMOtransmission, multiple Phased Antenna Arrays (PAAs) or a PAA withmultiple polarizations may be implemented in 802.11ay compatibledevices.

The EDMG Capability element may include the antenna polarizationcapability of an EDMG STA. An EDMG STA may transmit a MIMO Setup frame(e.g., request to send (RTS) or DMG clear to send (CTS)-to-self) priorto the transmission of a SU or MU MIMO PPDU. The MIMO Setup frame mayindicate one or more destination STA(s) addressed by the PPDU. A MIMOSetup frame (e.g., RTS) transmission may trigger a response (e.g., DMGCTS or Acknowledgment (ACK)) from one or more destination STA(s).

FIG. 8 is an exemplary EDMG PPDU format. The EDMG PPDU format mayinclude fields/subfields of one or more L-STF 802, L-CEF 804, L-HEADER806, EDMG-HEADER-A 808, EDMG-STF 810, EDMG-CEF 812, EDMG-HEADER-B 814,DATA 816, AGC 818, or TRN 820.

Multiple input multiple output (MIMO) setup mechanisms may be provided.MIMO setup frame may be used for multiple user (MU)-MIMO setup frame andsingle user (SU)-MIMO setup frame. MIMO setup frame may (e.g., in802.11ay) set up SU-MIMO and/or downlink (DL) MU-MIMO transmissions.With sub 6 GHz transmission, it may not be required to transmit a frameto set up MIMO transmission. With an mmW environment, transmissions maybe highly directional. In a single input single output (SISO) case, atransmitter and/or a receiver may prepare (e.g., need to prepare) atransmitter and/or a receiver's Tx/Rx beams (e.g., a transmitter and/ora receiver's own fixed Tx/Rx beams which point to each other). With anMIMO transmission, beam settings may be different for differentspatial/MIMO schemes. A control frame may be used to set up one or morebeams at the transmitter and/or receiver side. The frame may be designedto fulfill some or all the MIMO transmission scenarios.

Unintentional beamforming may occur. When multiple streams that comprisesame legacy fields (e.g., legacy short training field (STF), channelestimation field (CEF), and header) are transmitted from multipleantennas, power fluctuation (e.g., unintentional beamforming) may occuron the received signal, for example, due to a strong correlation betweentransmitted signals. A variation of received signal power may enable(e.g., cause) suboptimal AGC setting to decode a legacy header at alegacy device(s). This may be an issue when a STA aims atomnidirectional transmission by forming a quasi-omni antenna pattern,e.g., by changing the STA's own PAA configuration. In order todecorrelate the transmit signals, different cyclic shift may be appliedto a (e.g., each) transmitted signal. An operation of applying differentcyclic shift to a (e.g., each) transmitted signal may be compatible witha cyclic prefix (CP)-OFDM transmission(s), which may be addressed for asignal carrier system(s). A single carrier(s) may be adopted in IEEE802.11ad. IEEE 802.11ay may be compatible with 802.11ad receivers.

Channel estimation fields for multiple stream (MIMO) transmission may beused. A technology for reaching a high throughput (e.g., more than 20Gbps throughput) may comprise using multiple stream transmission (e.g.,SU-MIMO) via multiple transmit antennas. Mutually orthogonal channelestimation fields may be constructed, one for a (e.g., each) transmitantenna, for example, to enable SU-MIMO. One or more channel estimationfield(s) that are mutually orthogonal to each other and/or have the sameor similar properties as the channel estimation field(s) used in802.11ad may be identified (e.g., need to be identified).

MIMO transmission and setup implementations may be provided. In mmW,MIMO transmission (e.g., MIMO transmission that is different from SISO)may involve multiple radio frequency (RF) chains at Tx/Rx side or both.There may be one or more beam patterns to be adopted at Tx and/or Rxside. A Rx beam pattern may match or (e.g., need to) match a beampattern used at Tx side, for example, to achieve good BF performance.Beams used at the transmitter side may be signaled such that thereceiver may select matching receive beams, e.g., before MIMOtransmission. One or more beam modes and the usage of the beam modes maybe specified herein, e.g., type I beam modes and/or type II beam modes.For example, one or more of the following beam modes (e.g., type I beammodes) may be used.

Type I beam modes may include a basic quasi-omni mode and/or aquasi-omni mode for a single data stream transmission. One or more RFchains may be used. With more than one RF chain, a (e.g., each) RF chainmay form the RF chain's own quasi-Omni beam. In an example with two RFchains, the quasi-omni analog weight may be represented as W_(RF)^(QO)=[w_(RF1) ^(QO),w_(RF2) ^(QO)], where each w_(RFk) ^(Omni), k=1, 2,may be a vector of size N×1, and N is the size of antenna elementscontrolled by the RF chain.

With basic quasi-omni mode and/or quasi-omni mode for a single datastream transmission, baseband processing may include one or more of abaseband/digital domain precoding, a baseband/digital domain space-timecoding, a baseband/digital domain cyclic shift diversity (CSD), abaseband/digital domain antenna/polarization selection, and/or the like.A baseband/digital domain precoding may be used. In one or more of theexamples herein, the baseband weight may be W_(BB). The W_(BB) may bewith size 2×1, e.g., in the case that a single data stream may betransmitted. A transmit signal may be represented as, e.g., W_(RF)^(QO)W_(BB)s. The baseband precoding vector may be represented as, e.g.,W_(BB), and/or may be implementation based, for example, once theprecoding scheme is set. The baseband precoding vector (e.g., W_(BB))may be applied to the CEF field, e.g., the same way as basebandprecoding vector may be applied to data portion. The baseband precodingvector may be transparent to the receiver. A baseband/digital domainspace-time coding may be used. In one or more of the examples herein,two baseband symbols may be used and/or may be allocated in differenttime and/or frequency.

Type I beam modes may include a directional mode for SU-MIMO with asingle data stream transmission, a directional mode for SU-MIMO with amulti-data stream transmission, a directional mode for MU-MIMO with asingle data stream transmission for a (e.g., each) user and/or adirectional mode for MU-MIMO with a multi-data stream transmission for a(e.g., each) user.

An analog beam mode(s) may be set up and/or specified, e.g., when hybridbeamforming may be utilized in the system. The digital precoding/beamsmay be changed on the fly. For example, one or more of the followingbeam modes, which may be referred to as type II beam modes, may be used.Type II beam modes may include K quasi-omni beams, where K<=Kmax is thenumber of RF chains and/or the number of analog beams used for atransmission. Kmax may be the maximum number of RF chains availableand/or the maximum number of analog beams formed by a device. The valueof K may be specified and/or signaled in the system. Type II beam modesmay include K directional beams for SU-MIMO, where K<=Kmax is the numberof RF chains and/or the number of analog beams used for thetransmission. Kmax is the maximum number of RF chains available and/orthe maximum number of analog beams formed by the device. The value of Kmay be specified and/or signaled in the system. The indices of analogbeams (e.g., selected analog beams) may be signaled, e.g., in the caseK<Kmax. Type II beam modes may include K directional beams for DLMU-MIMO, where K=Σ_(u=1) ^(Nu)K_(u)≤K_(max) is the total number of RFchains and/or the number of analog beams used for the transmission tothe Nu users. Kmax may be the maximum number of RF chains availableand/or the maximum number of analog beams formed by the transmitterdevice. The value of K, and/or Ku, u=1, . . . , Nu, may be specifiedand/or signaled in the system. The indices of selected analog beamsand/or the analog beams assigned for a (e.g., each) user may besignaled. Digital/baseband domain spatial schemes may be applied, e.g.,if the number of data streams to be transmitted may be less than Kdescribed herein. The analog beams to be used may be fixed to the Kspecified beams.

Transmissions of DMG and/or EDMG frames may be switched between or amongbeam modes (e.g., the beam modes described herein). It may be possibleto switch beam modes from legacy preamble portion (e.g., includingLegacy Short Training Field (L-STF), Legacy-channel estimation (L-CE),L-Header, EDMG-Header-A fields) to EDMG portion (e.g., includingEDMG-STF, EDMG-CE, EDMG-Header-B and data fields), for example, with anEDMG PPDU transmission. Beam modes for the training (TRN) field may besignaled in a PHY header, for example, in the case a BRP TRN field maybe appended at the end of the PPDU.

Some beam mode(s) may be specified as a default beam mode(s). Thedefault beam mode(s) may be used for certain transmission(s) which maynot require an (e.g., any) explicit beam set-up. Receivers may expecttransmission(s) with default mode(s), for example, if there is little orno signaling to explicitly signal usage of a beam mode(s). The usage oftransmitting certain frames with certain beam mode(s) may be specified.For example, a default beam mode selection may follow one or more of thefollowing rules.

The default beam mode selection may follow the rule that the beam modemay be basic quasi-omni mode or quasi-omni mode for a single data streamtransmission with a fixed baseband scheme if a type I beam mode(s) isadopted, e.g., for broadcast or multicast management and/or controlframes (e.g., Beacon frames, announcement frames etc.). For example,basic quasi-omni mode or quasi-omni mode for a single data streamtransmission with baseband precoding (e.g., quasi-omni analog beams withbaseband precoding) may be specified as a default beam mode forbroadcast and/or multicast management and/or control frames. Basicquasi-omni mode or quasi-omni mode for a single data stream transmissionwith baseband/digital domain space-time coding (e.g., quasi-omni analogbeams with baseband space time block code (STBC) like beam mode) may bespecified. Any basic quasi-omni mode or quasi-omni mode for single datastream transmission may be used. If a type II beam mode(s) is adopted, Kquasi-omni beams, where K<=Kmax is the number of RF chains or number ofanalog beams used for the transmission (e.g., with K=Kmax or K=1) may beused for broadcasting and/or multicasting management/control frames. Abeam mode(s) may be specified in a standard and/or the beam mode(s) maybe set up in a beacon frame. The default beam mode may be fixed and/orused in a beacon interval, for example, when beam modes may be set up ina beacon frame. In a beacon interval (e.g., a different beacon intervalfrom the beacon interval where the default beam mode may be fixed andused), the default beam mode may be announced by the AP/PCP (e.g., againin a beacon frame). The default beam mode used in a previous beaconinterval may be utilized, for example, if no different (e.g., new)default beam mode is announced.

The default beam mode selection may follow the rule that, for unicastmanagement/control frames, the default beam mode may be the same asbroadcast/multicast management/control frame (e.g., quasi-omni basedbeams). The default beam mode may be a directional beam(s). For example,when a type I beam mode(s) is adopted, a directional mode for SU-MIMOwith a single data stream transmission(s) may be utilized. When a typeII beam mode(s) is adopted, K directional beams for SU-MIMO, whereK<=Kmax is the number of RF chains or the number of analog beams usedfor the transmission (e.g., with K=Kmax or K=1), may be used.

The default beam mode selection may follow the rule that, for dataframes without explicit beam setup, the default beam mode may be adirectional beam(s). For example, when a type I beam mode(s) is adopted,a directional mode for SU-MIMO with a single data stream transmission(s)may be utilized. When type II beam mode(s) is adopted, K directionalbeams for SU-MIMO, where K<=Kmax is the number of RF chains or number ofanalog beams used for the transmission (e.g., with K=Kmax or K=1), maybe used.

The default beam mode selection may follow the rule that, for dataframes with an explicit beam setup, the beam mode may follow a beamsetup field. The beam setup field may be carried in one or more of aMIMO setup frame, a multi-channel setup frame, a beacon frame, anallocation field, a schedule element, an extended schedule element,and/or the like.

MU-MIMO implementations may be provided. A network entity (e.g., anaccess point) may group MU-MIMO users, for example, based on acharacterization of a beam(s) and/or a ranking of a beam(s). Thecharacterization of a beam(s) may include a good beam (e.g., best beams)and/or a bad beam (e.g., worst beams). A good beam(s) and a best beam(s)may be used interchangeably. A bad beam(s) and a worst beam(s) may beused interchangeably. The AP may provide beam (e.g., analog beams)and/or antenna (e.g., virtual antenna) allocation. The grouping orseparation of stations (e.g., stations associated with users) may beperformed in various ways for different transmissions. For example, witha DL MU-MIMO transmission(s), the AP may perform the grouping orseparation of stations in a spatial domain. In an example, analogbeamforming and/or hybrid beamforming may be applied for grouping orseparating the stations. Hybrid beamforming may include analog anddigital beamforming techniques. With mmW transmission (e.g., when hybridbeamforming is applied), one or more techniques may be used to group orseparate the stations. For example, analog beamforming may be used,analog/digital beamforming may be used, etc.

Analog beamforming may be used to separate and/or group stations (e.g.,stations associated with users). Beamforming may focus a transmissionfrom a transmitter (e.g., a virtual antenna) such that the transmissionbecomes more directional. Analog beamforming may enable a transmitter totransmit from multiple beams and/or RF chains. The AP/PCP may includeone or more antennas (e.g., virtual antennas). The stations (e.g.,stations associated with users) may include one or more antennas (e.g.,virtual antennas). Using analog beamforming and/or hybrid beamforming,an antenna(s) (e.g., a virtual antenna(s)) may transmit via one or morebeams (e.g., analog beams) and/or RF chains.

The AP/PCP may use inter-user interference information to perform userselection/pairing/grouping. The inter-user interference information mayinclude interference among transmissions to and/or from differentstations (e.g., stations associated with users). Various parameters ormetrics may be used to indicate the inter-user interference or theextent of the inter-user interference. For example, signal to noiseratio (SNR) or signal to interference plus noise ratio (SINR) may beused to characterize the inter-user interference or the extent of theinter-user interference. The inter-user interference information may beacquired in various ways. For example, inter-user interferenceinformation may be acquired by analog beam training, analog beamtracking, analog beam down selection, and/or the like.

The inter-user interference information may be acquired by analog beamtraining. During analog beam training (e.g., an extended SLSimplementation), a transmitter (e.g., the AP) may send from an antenna(e.g., a virtual antenna) of the transmitter one or more analogtransmissions. For example, an analog transmission may include atransmission through an analog beam that is formed with a virtualantenna.

The analog transmission may include various signaling. For example, theanalog transmission may be a sounding frame or signal. The virtualantenna of the transmitter may transmit via one or more analog beams(e.g., a transmission per beam). A receiver (e.g., a station) mayreceive via an antenna (e.g., a virtual antenna) of the receiver the oneor more analog transmissions. The virtual antenna of the receiver mayreceive the one or more analog transmissions via one or more analogbeams. For example, a beam of a virtual antenna of the station mayreceive some or all analog transmissions from the AP. An analogtransmission of the one or more analog transmissions may be communicatedfrom a beam of a virtual antenna of the AP to a beam of a virtualantenna of the station. The beam of the virtual antenna of the AP andthe beam of the virtual antenna of the station may form a TX and RX beampair. For example, the beam of the virtual antenna of the AP may be theTX beam in the beam pair. The beam of the virtual antenna of the stationmay be the RX beam in the beam pair. Different TX and RX beam pairs maybe associated with different inter-user interference information.Inter-user interference information may be measured, for example by thestation, and may be based on the analog transmission(s) communicatedbetween the TX and RX beams or beam pair. The virtual antenna of the APand the virtual antenna of the station may form a TX and RX virtualantenna pair. For example, the virtual antenna of the AP may be the TXvirtual antenna of the virtual antenna pair. The virtual antenna of thestation may be the RX virtual antenna of the virtual antenna pair.

The inter-user interference information may be acquired by analog beamtracking. For example, analog beam tracking may be performed as anone-to-multiple sector level sweeping between an AP and STAs and/or aone-to-one sector level sweeping between an AP and an STA. Analog beamtracking may be performed as one-to-multiple sector level sweepingbetween an STA and STA(s) and/or one-to-one sector level sweepingbetween an STA and another STA. Analog beam tracking may be part of anMIMO BF training implementation. For example, analog beam tracking maybe an SISO phase of an enhanced BF training. During analog beam tracking(e.g., an extended BRP implementation), the AP/PCP may transmit atraining sequence one or more times using one or more beams or beamcombinations. The training sequence may include one or more analogtransmissions through one or more analog beams or beam combinations. TheAP/PCP may be configured to track the one or more beams or beamcombinations. The AP/PCP may determine and/or identify the one or morebeams or beam combinations to track.

The inter-user interference information may be acquired by analog beamdown selection. During analog beam down selection (e.g., an extended SLSimplementation and/or an extended BRP implementation and/or SLSimplementation using a BRP frame(s)), the AP/PCP may transmit a trainingsequence or a training frame(s) using one or more beams or beamcombinations. The training sequence or training frame(s) may include oneor more analog transmissions. An STA(s) may report feedback (e.g.,channel measurements such as SNR or CSI) back to an AP/PCP. The AP/PCPmay be configured to downselect the one or more beams or beamcombinations based on the feedback. The AP/PCP may determine and/oridentify the one or more beams or beam combinations to downselect and/orperform an SU/MU-MIMO BF training (e.g., a further SU/MU-MIMO BFtraining).

The acquired inter-user interference information may be used, forexample by the station, to determine a characterization of a beam and/orbeam pair. Some beams and/or beam pairs may be characterized as good(e.g., best) beams and/or beam pairs. Some beams and/or beam pairs maybe characterized as bad (e.g., worst) beams and/or beam pairs. Theinter-user interference information may be used to compare with one ormore thresholds (e.g., a relatively higher threshold and/or a relativelylower threshold) to determine the best and/or worst beam/beam pairs. Theinter-user interference information may be used to compare withdifferent inter-user interference information measured based on atransmissions(s) via a different beam(s)/beam pair(s) and/or via adifferent antenna(s)/antenna pair(s) to determine the best and/or worstbeam/beam pairs. The beams and/or beam pairs and/or theantenna(s)/antenna pair(s) may be ranked based on the inter-userinterference information.

In an example, an SNR threshold may be used for characterizing the beamsand/or beam pairs. The beams and/or beam pairs associated with an SNRthat is greater or equal to the SNR threshold may be characterized asbest beams and/or beam pairs. The beams and/or beam pairs associatedwith an SNR that is less than the SNR threshold may be characterized asworst beams and/or beam pairs. As described herein, a Tx and Rx virtualantenna pair may include one or more beams and/or beam pairs.

A beamformee (e.g., the station) may feed back information including orindicating the best few beams and/or beam pairs for a (e.g., each) Txand Rx virtual antenna pair. A beamformee (e.g., the station) may feedback information including or indicating the worst few beams for the(e.g., each) Tx and Rx virtual antenna pair. For example, the stationmay feed back the best and/or the worst few beams to the AP/PCP via anindication(s). The indication(s) may include a frame(s) or be sent via aframe(s). A beamformee (e.g., the station) may feed back informationincluding or indicating channel measurements such as an SNR(s)associated with a (e.g., each) triple <beam ID, Tx antenna ID, Rxantenna ID> and/or CSI associated with the triple <beam ID, Tx antennaID, Rx antenna ID>. For a pair (e.g., a fixed pair or a selected pair)of Tx antenna ID and Rx antenna ID, one or more beam IDs associated withbest and/or worst beams may be selected and/or reported. The one or morebeam IDs may be associated with one or more best and/or worst beams/beampairs.

The AP/PCP may receive the indication(s) and/or use the indication(s) togroup and/or separate users and/or stations. The implementationsdescribed herein may be applicable to one or more stations. For example,the AP/PCP may receive, from one station, an indication of the best beamof the AP/PCP for the station. The best beam of the AP/PCP for thestation may be identified/selected from multiple beam/beam pairs for aTx and Rx virtual antenna pair. The AP/PCP may receive, from anotherstation, an indication of the worst beam of the AP for that otherstation for another Tx and Rx virtual antenna pair. The AP/PCP maydetermine based on one or more of the indications for multiple stationsthat the best beam for one station may be among the worst beams foranother station. The AP/PCP may determine based on one or more of theindications for multiple stations that a virtual antenna of the AP/PCPmay include the best beam for one station, and that that another virtualantenna of the AP/PCP may include the best beam for another station. TheAP/PCP may determine to group the two stations for transmissions (e.g.,DL MU-MIMO transmissions). The AP/PCP may indicate to both stationsabout the grouping.

In the example, the AP/PCP may indicate to the stations about theallocation of the respective beam/RF chain/virtual antenna allocation tothe respective station. The AP/PCP may perform the allocation to thestations for a DL MU-MIMO transmission(s). For example, the allocationmay be performed using one or more of the triples <beam ID, Tx antennaID, Rx antenna ID> with (e.g., plus) a user ID(s) and/ or a spatialstream ID(s), for example, if an allocation of the spatial stream to theuser may be explicit. For example, the AP/PCP may have four beams/RFchains/virtual antennas (e.g., virtual antennas 1-4). The AP/PCP maytransmit to user 1 (e.g., station 1 associated with user 1) and user 2(e.g., station 2 associated with user 2) through DL MU-MIMO. As anexample, the AP/PCP may allocate beam/RF chain/virtual antennas 1 and 2to user 1 based on one or more indications. The AP/PCP may allocatebeam/RF chain/virtual antennas 3 and 4 to user 2 based on one or moreindications.

Stations (e.g., stations associated with users) may be separated byanalog/digital beamforming. With the analog/digital beamformingtechnique, the stations (e.g., stations associated with users) may notbe totally separated by the analog beams. As an example, the AP/PCP maynot require inter-user interference feedback. The AP/PCP may groupstations (e.g., stations associated with users) and/or perform aninter-user interference cancellation in baseband/digital domain. TheAP/PCP may stop the MU-MIMO, e.g., when MU-MIMO transmission failure maybe observed. The AP/PCP may use (e.g., require) partial inter-userinterference feedback. The AP/PCP may group stations (e.g., stationsassociated with users) based on the partial inter-user interferencefeedback and/or perform an inter-user interference cancellation inbaseband/digital domain.

The allocation of the respective beam/RF chain/virtual antenna to therespective station may be set up, for example by the AP, and/or signaledin an MIMO setup frame and/or other frames (e.g., if stations areseparated by analog beamforming or by analog/digital beamforming). Forexample, the allocation of the respective beam/RF chain/virtual antennato the respective station may be signaled in an MIMO setup frame beam toalign the beams/RF chains/virtual antennas at TX and RX sides.

Detailed MU-MIMO user grouping and/or beam/antenna allocation may bedescribed herein. FIG. 9 may refer to specific beams, virtual antennas,and stations, but the specific beams, virtual antennas, and stations arefor illustrative purposes. The beams, virtual antennas, and stations maybe paired in various ways (e.g., depending on implementations). Anynetwork entity, station, antenna, virtual antenna may perform theimplementation or feature (e.g., determining the best beam or worstbeam) herein.

FIG. 9 shows an example of a MU-MIMO user selection and/or beam/antennaallocation using analog beam training, tracking, down selection and/orrefinement. The technique as shown in FIG. 9 may be implemented usingsector level sweep and/or beam refinement protocol and/or an extendedversion of SLS and BPR protocol. In the example of FIG. 9, the AP/PCP902 may include 4 virtual antennas 906-912 (e.g., PAAs, and/or a PAAwith multiple polarizations). Virtual antennas 906-912 may each form 8analog beams. STA 904 and STA 962 may be potential beamformees. STA 904may have 2 virtual antennas 914 and 916. STA 962 may have 2 virtualantennas 918 and 920. Virtual antennas 914 and 916 may each form 8analog beams. Virtual antennas 918 and 920 may each form 8 analog beams.The implementation and/or structures described herein may be used in oneor more examples herein. The implementation and/or structures herein maybe extended to any number of virtual antennas and/or stations (e.g.,stations associated with users).

The AP/PCP 902 may perform analog beam training, tracking, downselection and/or or refinement (e.g., by sweeping AP/PCP's transmitanalog beams) with one or more STAs. The AP/PCP 902 may sweep beams witha (e.g., one) virtual antenna at a time with a random or a preselectedorder. For example, the AP/PCP 902 may sweep beams with virtual antenna906 and sweep virtual antenna 908 after the AP/PCP 902 completessweeping beams with virtual antenna 906. The AP/PCP 902 may sweep beamswith virtual antenna 910 and/or virtual antenna 912 (e.g., in a similarway or a different way). The order in which the AP/PCP 902 works throughthe virtual antennas (e.g., virtual antennas 906-912) may vary. Forexample, the AP/PCP 902 may sweep 8 beams including beams 922-928. TheAP/PCP 902 may transmit multiple analog transmissions via the 8 beamsassociated with the virtual antenna 906. The AP/PCP 902 may transmit ananalog transmission per beam. For example, the AP/PCP 902 may transmitan analog transmission via beam 922. The analog transmissions mayinclude a sounding signal or a sounding frame. The STA 904 may receivethe transmission from beam 922 at the virtual antenna 914 and/or virtualantenna 916 of the STA 904. For example, the virtual antenna 914 mayinclude 8 beams including beams 938-942. The STA 904 may receive theanalog transmission from beam 922 at one, some, or all 8 beams of thevirtual antenna 914. The STA 904 may measure inter-user interferenceinformation of an analog transmission(s) for a TX and RX beam pair.

The STA 904 may characterize a TX and RX beam pair based on inter-userinterference information measured on an analog transmission that the STA904 receives via the TX and RX beam pair. The STA 904 may characterizethe analog transmission based on the measured inter-user interferenceinformation and/or characterize the TX and RX beam pair based on thecharacterization of the analog transmission. For example, the inter-userinterference information may include SNR and/or SINR. In the exampleshown in FIG. 9, the STA 904 may measure the SNR of the transmissionthat the STA 904 received via the TX beam 922 and RX beam 938 pair. TheSTA 904 may characterize the transmission that the STA 904 received viathe TX beam 922 and RX beam 938 pair. The STA 904 may rank thetransmission that the STA 904 received via the TX beam 922 and RX beam938 pair among the transmission(s) that the STA 904 received via otherTX beam and RX beam pairs. The STA 904 may rank the transmission thatthe STA 904 received via the TX beam 922 and RX beam 938 pair among thetransmission(s) that the STA 904 received via the beam pair of TX beam922 and other RX beams (e.g., the TX 922 and RX 942 beam pair) atvirtual antenna 914. The STA 904 may rank the analog transmission thatthe STA 904 received via the TX beam 922 and RX beam 938 pair amonganalog transmissions that the STA 904 received from other beams ofvirtual antenna 906 including beams 922-928 (e.g., the TX 928 and RX 938beam pair). The STA 904 may rank analog transmissions associated withrelatively higher SNR or SINR higher than other analog transmissionsassociated with relatively lower SNR or SINR.

A STA may characterize a transmission (e.g., an analog transmission)that the STA receives via a TX and RX beam pair, for example as a bestanalog transmission or a worst analog transmission, based on one or morethresholds of inter-user interference information and/or based on acomparison of inter-user interference information (e.g., between beamsor beam pairs). The STA 904 may receive one or more SNR thresholds ordetermine one or more preconfigured SNR thresholds to use. In theexample shown in FIG. 9, the STA 904 may measure the SNR of the analogtransmission that the STA 904 received via the TX beam 922 and RX beam938 pair. The STA 904 may compare the measured analog transmission witha relatively higher SNR threshold that the STA 904 received. If themeasured analog transmission is greater than the relatively higher SNRthreshold, the STA 904 may determine that the measured analogtransmission is a best analog transmission. The STA 904 may receive arelatively lower SNR threshold. The STA 904 may compare the measuredanalog transmission with the relatively lower SNR threshold. If themeasured analog transmission is less than the relatively lower SNRthreshold, the STA 904 may determine that the measured analogtransmission is a worst analog transmission.

The STA may characterize a TX beam, a RX beam, or a TX and RX beam pairas a best beam/beam pair or a worst beam/beam pair based on thecharacterization of the analog transmission that the STA received viathe TX beam, the RX beam, or the TX and RX beam pair. In the exampleshown in FIG. 9, the STA 904 may receive the analog transmission frombeam 922 to the beams at virtual antenna 914. The STA 904 may measurethe SNR(s) of the analog transmission at one, some, or all 8 beamsincluding beams 938-942. For example, the STA 904 may measure the SNR ofthe analog transmission between the TX 922 and RX 938 beam pair (922/938analog transmission) and/or compare the measured SNR with the relativelylower SNR threshold. The STA 904 may determine that the measured SNR isless than the relatively lower SNR threshold and/or determine that the922/938 analog transmission is the worst analog transmission. The STA904 may measure the SNR of the analog transmission between the TX 924and RX 942 beam pair (924/942 analog transmission) and/or compare themeasured SNR with the relatively higher SNR threshold. The STA 904 maydetermine that the measured SNR is greater than the relatively higherSNR threshold and/or determine that the 924/942 analog transmission isthe best analog transmission. The STA 904 may determine that the TX 924and RX 942 beam pair is the best beam pair based on the determinationthat the 924/942 analog transmission is the best analog transmission.The STA 904 may determine that the TX 924 beam and/or the RX 942 beam isthe best beam based on the determination that the 924/942 analogtransmission is the best analog transmission. The STA 904 may determinethat the 922/938 analog transmission is the worst beam pair based on thedetermination that the 922/938 analog transmission is the worst analogtransmission. The STA 904 may determine that the TX 922 beam and/or theRX 938 beam is the worst beam(s) based on the determination that the922/938 analog transmission is the worst analog transmission.

The STA may associate the determination of the best beam/beam pairand/or the worst beam/beam pairs with a virtual antenna pair. In theexample shown in FIG. 9, the Tx beam 924 is from virtual Tx antenna 906,and the Rx beam 942 is from virtual Rx antenna 914. The STA 904 maydetermine that, for the virtual antenna pair 906 and 914, the best beampair is the TX 924 and RX 942 beam pair based on the determination ofthe best beam pair as discussed herein. In a similar or same way, theSTA 904 may determine that, for the virtual antenna pair 908 and 916,the best beam pair is the TX 932 and RX 940 beam pair.

The STA 904 may be aware of or be able to identify, for the best and/orworst beam(s)/beam pair(s), the AP/PCP, the virtual antenna(s) of theAP/PCP, the beams of the virtual antennas of the AP/PCP, the station,the virtual antenna(s) of the station, the beams of the virtual antennasof the station, each of which is associated with the best and/or worstbeam(s)/beam pair(s). The AP/PCP, the virtual antenna(s) of the AP/PCP,the beam(s) of the virtual antenna(s) of the AP/PCP, the station(s), thevirtual antenna(s) of the station(s), and/or the beams of the virtualantenna(s) of the station may be associated with an index and/oridentification. The index and/or identification may be communicatedbetween the AP/PCP and the station(s), for example, via a frame(s). Forexample, the AP/PCP 902 may send a sounding frame from the beam 924 ofthe virtual antenna 906. The sounding frame may include anidentification of the beam 924 (e.g., a beam ID) and/or anidentification of the virtual antenna 906 (e.g., a virtual antenna ID).A frame may include an identification by which the AP/PCP may associatewith the AP/PCP's TX virtual antenna ID and TX beam ID. Theidentification by which the AP/PCP may associate with AP/PCP's TXvirtual antenna ID and TX beam ID may be unique. The station 904 mayreceive a frame (e.g., the sounding frame) via the beam 942 at thevirtual antenna 914. The station 904 may determine that the best analogtransmission is associated with the TX 924 and RX 942 beam pair. Thestation 904 may determine that the best analog transmission isassociated with the TX 906 and RX 914 antenna pair. The station 904 mayfeed back the determination(s) to the AP/PCP 902. The feedbackinformation may include or indicate channel measurements such as anSNR(s) measurement or CSI for an (e.g., each) combination and/or set <Txantenna ID, Rx antenna ID, Rx beam ID, Rx beam ID>. A Rx antenna ID(s)and/or Rx beam ID(s) may not be explicit. A receiver (e.g., the station904) may determine and/or associate the Rx antenna ID(s) and/or Rx beamID(s) with a corresponding Tx antenna ID(s) and/or Tx beam ID(s).

A station (e.g., STA 904) may use the implementations described hereinto determine best and/or worst beam/beam pairs for other virtual antennapairs. In the example shown in FIG. 9, the STA 904 may determine thatthe best TX beam for the TX 908 and RX 914 antenna pair is the beam 930,and the worst TX beam for the TX 908 and RX 914 antenna pair is the beam936. The STA 904 may determine that the best TX beam for the TX 910 andRX 914 antenna pair is the beam 948, and the worst TX beam for the TX910 and RX 914 antenna pair is the beam 944. The STA 904 may determinethat the best TX beam for the TX 912 and RX 914 antenna pair is the beam954, and the worst TX beam for the TX 912 and RX 914 antenna pair is thebeam 958. The STA 904 may determine that the best TX beam for the TX 906and RX 916 antenna pair is the beam 926, and the worst TX beam for theTX 906 and RX 916 antenna pair is the beam 928. The STA 904 maydetermine that the best TX beam for the TX 908 and RX 916 antenna pairis the beam 932, and the worst TX beam for the TX 908 and RX 916 antennapair is the beam 934. The STA 904 may determine that the best TX beamfor the TX 910 and RX 916 antenna pair is the beam 950, and the worst TXbeam for the TX 910 and RX 916 antenna pair is the beam 944. The STA 904may determine that the best TX beam for the TX 912 and RX 916 antennapair is the beam 960, and the worst TX beam for the TX 912 and RX 916antenna pair is the beam 958. The STA 904 may record and/or store one ormore of the determinations (e.g., in a volatile or non-volatile memory)

One or more stations may use the implementations described herein todetermine best and/or worst beam/beam pairs for a virtual antenna(s). Inthe example shown in FIG. 9, the STA 962 may determine that beam 924 andbeam 932 are not the best TX beams (e.g., among the worst beams) forvirtual antenna 918 or virtual antenna 920. The STA 962 may determinethat beam 944 and beam 958 are among the best beams (e.g., are the bestTX beams) for the STA 962. For example, the STA 962 may determine thatthe beam 944 is the best TX beam for virtual antenna 918 correspondingto the RX beam 964, and that the beam 958 is the best TX beam forvirtual antenna 920 corresponding to the RX beam 966.

In one or more examples, the AP/PCP may determine best and/or worstbeam/beam pairs for a virtual antenna(s) based on the inter-userinterference information that the AP/PCP receives from one or morestations. For example, in FIG. 9, the AP/PCP 902 may receive inter-userinterference information for one or more beam/beam pairs for virtualantenna pair 906 and 914. The AP/PCP 902 may receive inter-userinterference information via a frame. The AP/PCP 902 may receive one ormore thresholds of the inter-user interference information. The AP/PCP902 may determine one or more thresholds of the inter-user interferenceinformation based on a preconfigured specification or indication. TheAP/PCP 902 may compare the received inter-user interference informationwith the threshold and/or determine the best and/or worst beam/beampairs. The AP/PCP 902 may compare the received inter-user interferenceinformation with each other and/or determine the best and/or worstbeam/beam pairs.

The AP/PCP may train multiple beams simultaneously, e.g., by usingmultiple virtual antennas concurrently. The AP/PCP may not sweep all thepossible analog beams, e.g., may sweep a subset of the possible analogbeams (e.g., determined analog beams).

The STA 904 may feed back that with VA2 at the STA1, the best beam fromAP VA1 is beam x; the best beam from AP VA2 is beam 3; the best beamfrom AP VA3 is beam x; the best beam from AP VA4 is beam x; andcorresponding SNRs/SINRs. The information may comprise that with VA2 atthe STA1, the worst beam from AP VA1 is beam x; the worst beam from APVA2 is beam x; the worst beam from AP VA3 is beam 6; the worst beam fromAP VA4 is beam 7, and corresponding SNRs/SINRs. For the worst beams, themeasurements (SNR/SINR) may be dominated by noise and/or interference.The measurements may or may not be reliable. In that case, a set of beamindices which may have SNR or SINR measured below certain threshold maybe fed back. The best beam and/or worst beam may be utilized in one oremore examples herein.

The STA 904 (STA1) may feed back one or more indications (e.g., via aframe) to the AP/PCP 902 indicating the characterization of thebeam/beam pairs. For example, the STA 904 may feed back an indication tothe AP/PCP 902 indicating the best beam beam(s)/beam pair(s) for avirtual antenna pair. The STA 904 may feed back an indication thatcomprises the following information, e.g., on reception of the analogbeam training frames. The information may comprise that, for virtualantenna 914 (VA1) at the STA1, the best beam from virtual antenna 906(AP VA1) is the TX beam 924 (beam 4). The information may comprise that,for virtual antenna 914 (VA1) at the STA1, the best beam from virtualantenna 908 (AP VA2) is the TX beam 930. The information may comprisethat, for virtual antenna 914 (VA1) at the STA1, the best beam fromvirtual antenna 910 (AP VA3) is the TX beam 948. The information maycomprise that, for virtual antenna 914 (VA1) at the STA1, the best beamfrom virtual antenna 912 (AP VA4) is the TX beam 954.

The STA 904 may feed back an indication to the AP/PCP 902 indicating theworst beam beam(s)/beam pair(s) for a virtual antenna pair. Theinformation may comprise that, for virtual antenna 914 (VA1) at theSTA1, the worst beam from virtual antenna 906 (AP VA1) is the TX beam922. The information may comprise that, for virtual antenna 914 (VA1) atthe STA1, the worst beam from virtual antenna 908 (AP VA2) is the TXbeam 936. The information may comprise that, for virtual antenna 914(VA1) at the STA1, the worst beam from virtual antenna 910 (AP VA3) isthe TX beam 944 (beam 6). The information may comprise that, for virtualantenna 914 (VA1) at the STA1, the worst beam from virtual antenna 912(AP VA4) is the TX beam 958 (beam 7).

The information may comprise corresponding SNRs/SINRs for the bestand/or worst beam/beam pairs for a virtual antenna pair. The informationmay comprise a set(s) of beam indices and/or corresponding SNR or SINRmeasured. For example, the set(s) of beam indices may include a triple<Tx antenna ID, Rx antenna ID, (Tx) beam ID>) and/or an identity whichmay be linked (e.g., uniquely linked) to the triple). Measurement of theinter-user interference information may be affected by noise and/orinterference. For example, for the worst beams, measurements (e.g.,SNR/SINR) may be dominated by noise and/or interference. The measurementmay not be reliable in such a case. The information may (e.g., in such acase) comprise a set of beam indices identifying a set of beam and/orbeam pairs. For example, the set of beam indices may include a triple(s)<Tx antenna ID, Rx antenna ID, and Tx beam ID>. The set of beam indicesmay include an identity which may be linked (e.g., uniquely linked) tothe triple. For example, the set of beam indices may include Tx antennaID, Rx antenna ID, and Tx beam ID or an identity which may be uniquelylink to the triple that have SNR or SINR measured below a certainthreshold (e.g., a relatively lower threshold).

The STA 904 (STA1) may feed back an indication (e.g., via a frame) tothe AP/PCP 902 with one or more of indications of the characterizationof the beam/beam pairs for additional virtual antennas/antenna pairs.For example, the STA 904 may indicate the following information, e.g.,on reception of the analog beam training frames. The information maycomprise that, for virtual antenna 916 (VA2) at the STA1, the best beamfrom virtual antenna 906 (AP VA1) is the TX beam 926. The informationmay comprise that, for virtual antenna 916 (VA2) at the STA1, the bestbeam from virtual antenna 908 (AP VA2) is the TX beam 932. Theinformation may comprise that, for virtual antenna 916 (VA2) at theSTA1, the best beam from virtual antenna 910 (AP VA3) is the TX beam950. The information may comprise that, for virtual antenna 916 (VA2) atthe STA1, the best beam from virtual antenna 912 (AP VA4) is the TX beam960.

The STA 904 may feed back an indication to the AP/PCP 902 indicating theworst beam beam(s)/beam pair(s) for additional virtual antennas/antennapairs. The information may comprise that, for virtual antenna 916 (VA2)at the STA1, the worst beam from virtual antenna 906 (AP VA1) is the TXbeam 928. The information may comprise that, for virtual antenna 916(VA2) at the STA1, the worst beam from virtual antenna 908 (AP VA2) isthe TX beam 934. The information may comprise that, for virtual antenna916 (VA2) at the STA1, the worst beam from virtual antenna 910 (AP VA 3)is the TX beam 944 (beam 6). The information may comprise that, forvirtual antenna 916 (VA2) at the STA1, the worst beam from virtualantenna 912 (AP VA 4) is the TX beam 958 (beam 7).

The STA 904 may feed back information about multiple best beam(s)/beampair(s) and/or multiple worst beam(s)/beam pair(s) to the AP/PCP. Theinformation may indicate the number of (e.g., K) best beams and/or thenumber of (e.g., N) worst beams. K and/or N may be set by the AP/PCP ina training frame(s), a training setup frame(s), a beacon frame(s) orother kind of control/management frames transmitted by the AP/PCP. Oneor more of the training frame(s), the training setup frame(s), thebeacon frame(s) or other kind of control/management frames transmittedby the AP/PCP may include one or more SNR threshold(s). The one or moreSNR threshold(s) may be preconfigured. K and N may be the same ordifferent from each other. K and/or N may be specified in a standardexplicitly or implicitly.

The implementations herein may be for illustrative purposes. Any STA(s)may perform the features herein, and/or may determine the bestbeam(s)/beam pair(s) and/or worst beam(s)/beam pair(s) in a transceiverand/or a receiver. A STA may determine that one or more beams/beam pairsor none of beams/beam pairs for a virtual antenna pair are the bestbeams/beam pairs. A STA may determine that some or all beams/beam pairsor none of beams/beam pairs for a virtual antenna pair are the worstbeams/beam pairs.

One or more stations may feed back indications to one or more AP/PCPs asdescribed herein. In the example shown in FIG. 9, the STA 962 (STA2) mayfeed back an indication (e.g., via a frame) to the AP/PCP 902 with oneor more of indications of the characterization of the beam/beam pairsfor a virtual antenna pair(s). The STA 962 may feed back an indicationthat comprises the following information, e.g., on reception of theanalog beam training frames. The indication that is fed back by STA 2may be the same as or similar to an indication that is fed back by STA 2(e.g., in format). The indication that is fed back by STA 2 may be basedon STA2's measurement. For example, the indication may indicate thatbeam 4 from AP VA1 and/or beam 3 from AP VA1 are not the best beams(e.g., among the worst beams) for STA2. The frame may indicate that beam7 from AP VA3 and/or beam 7 from AP VA4 are among the best beams (e.g.,the best beams) for STA2.

The configurations and/or implementations herein are for illustrativepurposes only. For example, the best TX beam for station 904 and theworst TX beams for station 962 may or may not over lap. If the best TXbeam for station 904 and the worst TX beams for station 962 do not overlap, the AP may group or attempt to group the station 904 and/or thestation 962 with a station different from either the station 904 or thestation 962.

The AP/PCP 902 may receive one or more of the indications herein fromSTA 1 and/or STA 2. The AP/PCP 902 may perform user grouping orseparation based on one or more of the indications. The AP/PCP 902 mayuse certain rules and/or processes to group or separate the stations(e.g., stations associated with users). The rules and/or processes usedmay depend on an implementation. For example, the AP/PCP 902 may groupstations (e.g., stations associated with users) to minimize theinter-user interference. The AP/PCP may pair or group the STAs forMU-MIMO transmissions. For example, the AP/PCP 902 may group thestations that have the best beam(s) and/or beam pair(s). The AP/PCP 902may group the stations that have the worst beam(s) and/or beam pair(s).The AP/PCP 902 may group a station that has the best beam(s) and/or beampair(s) and a station that has the worst beam(s) and/or beam pair(s).

The AP/PCP 902 may send an indication of the grouping to one or morestations (e.g., the stations concerned in the grouping). The indicationof the grouping may include identifications for the stations. Theindication of the grouping may include antenna/beam configurations,which may include the triple <Tx antenna ID, Rx antenna ID, Tx beam ID>for a (e.g., each) user/spatial stream. An antenna/beam configurationmay include information which may be used to derive the triple <Txantenna ID, Rx antenna ID, Tx beam ID> for a (e.g., each) user/spatialstream.

The AP/PCP 902 may perform antenna allocation based on one or more ofthe indications. In the example shown in FIG. 9, as described herein, APVA1 and AP VA2 may include the best beams (e.g., that may be among theworst beams for STA2) for STA1, and AP VA3 and AP VA4 may include thebest beams (e.g., that may be among the worst beams for STA1) for STA2.The AP/PCP 902 may allocate AP VA1 and AP VA2 to STA1. The AP/PCP mayallocate AP VA3 and AP VA4 to STA2. STA1 and/or STA2 may be aware of thecorresponding VA(s) to use based on the determination of the bestbeam/beam pairs as described herein.

The AP/PCP 902 may perform beam allocation based on one or more of theindications. In the example shown in FIG. 9, as described herein, AP VA1and AP VA2 may include the best beams. For example, beam 4 may have beendetermined as the best beam for the AP VA1/VA1 pair. Beam 3 may havebeen determined as the best beam for the AP VA2/VA2 pair. The AP/PCP 902may allocate beam 4 of AP VA1 to STA 1 and/or beam 3 of AP VA2 to STA 1.STA1 may be aware of the corresponding beam(s) and/or VAs to use basedon the determination of the best beam/beam pairs as described herein.

The AP/PCP 902 may indicate and/or signal the beam/antenna allocation toa station(s). The grouping indication may include the beam/antennaallocation. For example, the AP/PCP 902 may indicate and/or signal thebeam/antenna allocation in an MIMO setup frame or other frames (e.g., toalign the beams at TX and RX sides). STA1 and/or STA2 may prepare STA1'sand/or STA2's corresponding receive antennas/beams. An indication (e.g.,the indication of the grouping) may indicate beam/antenna allocation. Inthe example shown in FIG. 9, the beam allocation signaling in thisexample may include [STA1: VA1, Beam 4; VA2, Beam 3] and [STA2: VA3,Beam 6; VA4, Beam 7]. The beam allocation signaling in this example mayinclude [STA1: Tx VA1, Tx Beam 4, Rx VA1; Tx VA2, Tx Beam 3, Rx VA2]and/or [STA2: Tx VA3, Tx Beam 6, Rx VA1; Tx VA4, Tx Beam 7, Rx VA2].

A specific beam allocation and/or detailed beam indices may be omittedin some cases. For example, an AP/PCP and stations may agree on certainbeams. The beams may be optimum beams for the AP/PCP and/or the stationsin one or more aspects. For example, if optimum beams are agreed betweenthe AP/PCP and STA1/STA2, the signaling may be [STA1: VA1; VA2] and[STA2: VA3; VA4]. The signaling may use other formats. For example, abitmap may be used.

A MU-MIMO setup implementation may be provided. FIG. 10A may show anexemplary MU-MIMO setup implementation.

As shown in example FIG. 10A, STA 1002 (for example, an AP/PCP) maytransmit a MU-MIMO setup frame 1004. The MU-MIMO setup frame may be agrant frame depending on implementation. The MU-MIMO setup frame 1004may be transmitted in a default multicast control frame transmissionmode, e.g., basic quasi-omni mode or quasi-omni mode for single datastream transmission in type I or K quasi-omni beams in type II beammodes. STA 1014 may prepare the reception of MIMO setup frame 1004 usinga default beam mode. On reception of the response frame 1016 from STA1014, STA 1002 may poll STA 1020. STA 1002 may successfully receiveresponse frames 1016 and 1022 from STA 1014 and STA 1020. STA 1002 maytransmit MU-MIMO PPDUs to STA 1014 and STA 1020 as planned usingsignaled beam modes. STA 1002 may successfully receive response framesfrom some of the desired stations (e.g., stations associated withusers). STA 1002 may not successfully receive response frames from alldesired stations (e.g., stations associated with users). For example,STA 1002 may successfully receive response frame 1016 from STA 1014and/or may not successfully receive response frame 1022 from STA 1020.One or more schemes may be used if STA 1002 does not successfullyreceive response frame 1022.

The MU-MIMO setup frame 1004 may be transmitted in a default multicastcontrol frame transmission mode with a single-data-streamtransmission(s). As an example, the frame 1004 may be transmitted usinga legacy DMG PPDU. A header field may be detected by legacy users. Aquasi-omni antenna pattern may be used from the starting of a packet tothe end of data portion. The STA 1002 may use a (e.g., a single) RFchain to transmit the frame 1004, e.g., in the case that more than oneRF frontends/chains may be available at the STA 1002 side. Some or allof the RF chains may be utilized. Quasi-omni beams may be formed by a(e.g., each) RF chain. In one or more examples, the frame 1004 may betransmitted using a EDMG SU PPDU format. For example, a EDGM-Header-Bfield may not be present in the preamble. L-STF, Legacy long trainingfield (L-LTF), L-Header and/or EDMG-Header-A fields may be transmittedusing a single RF chain. L-STF, L-LTF, L-Header and/or EDMG-Header-Afields may be transmitted using some or all of the RF chains. Detailedtransmission techniques/procedures may be disclosed herein. ForEDMG-STF, EDMG-CE and data fields, STA 1002 may use a different antennapattern to transmit the fields. For example, the STA 1002 may usemultiple RF chains and/or change digital/baseband domain precoding tosupport one or more data stream transmission. The STA 1002 may use thesame antenna pattern to transmit both legacy portion and EDMG portion.The MAC packet carried by the DMG PPDU may be an EDMG MAC packet, which,for example, may be partially understood by the legacy users.

The MU-MIMO setup frame 1004 may be transmitted in a default multicastcontrol frame transmission mode with some part of the frame transmittedusing MU directional transmission mode. For example, STA 1002 mayutilize the MU-MIMO transmission beams that may be used for DL MU-MIMOdata transmission for the MU-MIMO setup frame. The frame 1004 may betransmitted using legacy DMG PPDU. The MU-MIMO beams may be used from abeginning of the transmission. The frame 1004 may be transmitted usingEDMG PPDU. The legacy preamble portion (e.g., including L-STF, L-CEF,L-Header and/or EDMG-Header-A fields) may be transmitted using aquasi-omni beam mode. The EDMG portion (e.g., including EDMG-STF,EDMG-CEF, EDMG-Header-B and/or data fields) may be transmitted using anMU-MIMO beam mode. With this mode, single data stream and/or multi datastream transmissions may be possible.

The MU-MIMO setup frame 1004 may be transmitted in a default multicastcontrol frame transmission mode with STA 1002 indicating thetransmission rules for the following UL response frames in the EDMG MIMOsetup MAC frame. For example, STA 1002 may indicate antenna/beam mode oranalog beam mode that is expected to be used by STA 1014 and/or STA 1020for response frame transmissions. For example, the triple <Tx antennaID, Rx antenna ID, Tx beam ID> for a (e.g., each) user/spatial stream orsimilar (e.g., equivalent) information may be carried. The indicationmay be omitted when the response frame may use a default beam mode totransmit. The default beam mode may be signaled by the AP/PCP in beaconlike management frames. The default beam mode may be specified by thestandard. STA 1002 may indicate the number of data streams for aresponse frame. STA 1002 may indicate baseband/digital spatial schemesused for a response frame, such as STBC, space frequency block code(SFBC), CSD, open loop precoding, closed loop precoding, and/orantenna/polarization selection. STA 1002 may indicate modulation andcoding schemes for the response frame. STA 1002 may indicate whether theresponse frame is poll based. If the response frame is poll based, STA1002 may indicate whether the response frame (e.g., the first responseframe) may be polled by STA1. STAs (e.g., STA 1014 and STA 1020) may beordered such that the response frames may be transmitted in differenttime slots using the order.

The MU-MIMO setup frame 1004 may be transmitted in a default multicastcontrol frame transmission mode with STA 1002 indicating thetransmission rules for a poll frame (e.g., poll frame 1006) to betransmitted by STA 1002 in the EDMG MIMO setup MAC frame, e.g., if thepoll frame is present. For example, STA 1002 may indicate beam mode oranalog beam mode that is expected to be used by STA 1002 for the pollframe transmissions. The indication may be omitted when the poll framemay use a default beam mode to transmit. The default beam mode may besignaled by the AP/PCP (e.g., STA 1002) in beacon like managementframes. The default beam mode may be specified by the standard. STA 1002may indicate baseband/digital spatial schemes used for a poll frame(e.g., poll frame 1006), such as STBC, SFBC, CSD, open loop precoding,close loop precoding, and/or antenna/polarization selection. STA 1002may indicate the number of data streams for poll frame modulation and/orcoding schemes for the poll frame.

The MU-MIMO setup frame 1004 may be transmitted in a default multicastcontrol frame transmission mode with STA 1002 indicating thetransmission rules for the MU-MIMO transmission to be transmitted by STA1002 in the EDMG MIMO setup MAC frame. For example, the EDMG MIMO setupMAC frame may include a common field and/or a user specific field. TheEDMG MIMO setup MAC frame may carry information (e.g., beam/antennaallocation information). The information may include beam mode or analogbeam mode for DL MU-MIMO transmission. STA 1002 may indicate the numberof beams/RF chains/virtual antennas available for a (e.g., each) user.STA 1002 may indicate the beam/RF chains/virtual antenna indicesassigned for a (e.g., each) user. For example, STA 1002 may have 4 RFchains, and STA 1002 may transmit to 2 users (e.g., STA 1014 and STA1020). STA 1002 may transmit two spatial streams to STA 1014 and onespatial stream to STA 1020. STA 1002 may transmit MU-MIMO transmission1010 to STA 1014 and MU-MIMO transmission 1008 to STA 1020. In thisexample, beam/antenna allocation may be performed and/or signaledexplicitly or implicitly. STA 1002 may allocate two beams/RFchains/virtual antennas to STA 1014 and two beams/RF chains to STA 1020.In a user specific field for STA 1014, STA 1002 may indicate that Txantenna 1, Tx beam x1, and Tx antenna 2, Tx beam y1 may be used pointingto STA 1014. Corresponding or expected Rx antenna ID for a (e.g., each)STA may be indicated explicitly or implicitly. In a user specific fieldfor STA 1020, STA 1002 may indicate that Tx antenna 3, Tx beam x2, andTx antenna 4, Tx beam y2 may be used pointing to STA 1014. Correspondingor expected Rx antenna ID for a (e.g., each) STA may be indicatedexplicitly or implicitly.

Beam/antenna allocation may be performed in unequal ways (e.g., fordifferent stations). Transmit power may be equally distributed among theusers (e.g., two stations associated with users) by assigning uniform TXpower per user. Transmit power may be unequally distributed among theusers (e.g., two stations associated with users) by assigning uniform TXpower per beam/antenna. For example, STA 1002 may allocate threebeams/RF chains/virtual antennas to STA 1014 and one beams/RF chains toSTA 1020. In a user specific field for STA 1014, STA 1002 may indicatethat Tx antenna 1, Tx beam x1, and Tx antenna 2, Tx beam y1 and Txantenna 3, Tx beam z1 may be used pointing to STA 1014. In a userspecific field for STA 1020, STA 1002 may indicate that Tx antenna 4, Txbeam x2 may be used pointing to STA 1014. Power allocation or powerallocation approach may be signaled, e.g., in the case with unbalancedbeam/antenna allocation. In the approach described herein, a (e.g., one)set of beams/VAs may be assigned to a (e.g., each) user. STA 1002 mayassign a few sets of beams/VAs to a (e.g., each) user (e.g., STA 1014and STA 1020). The sets of beams may be in an order. For example, thefirst choice may be a first set (e.g., in the order). In the case thefirst set may not succeed, the transmitter and/or receiver(s) may go toa second set etc.

The information may include baseband/digital spatial schemes used forMU-MIMO transmission for a (e.g., each) user frame, such as STBC, SFBC,CSD, open loop precoding, close loop precoding, and antenna/polarizationselection. Different spatial schemes may be allowed per user. Theinformation may include the number of data streams per user for MU-MIMOtransmission. The information may include modulation and coding schemesper user for MU-MIMO transmission. The information may include channelbonding/aggregation information per user.

The MU-MIMO setup frame may be transmitted in a default multicastcontrol frame transmission mode with STA 1002 indicating thetransmission rules for the following uplink (UL) ACK frames 1018 and/or1024, e.g., in the EDMG MIMO setup MAC frame. STA 1014 and STA 1020 mayuse the same beams as that used for DL MU-MIMO reception if antennareciprocity is assumed, e.g., in the case that UL MU-MIMO may be allowedfor ACK transmission.

STA 1014 and STA 1020 may use a different set of beams for transmission,e.g., in the case that ACK frames 1018 and/or 1024 may be transmittedone after another different time slot. STA 1002 may indicate beam modeor analog beam mode that is expected to be used by STA 1014 and STA 1020for ACK frame transmissions. The indication may be omitted when ACKframe 1018 and/or 1024 may use default beam mode to transmit. Thedefault beam mode may be signaled by the AP/PCP in beacon likemanagement frames. The default beam mode may be specified by thestandard. The default mode may be a quasi-omni transmission or adirectional single data stream transmission where the directional beamsmay be trained and/or agreed (e.g., previously).

STA 1002 may indicate the number of data streams for an ACK frame (e.g.,ACK frame 1018 and/or 1024). The indication of the number of datastreams may be omitted when an ACK frame (e.g., ACK frame 1018 and/or1024) may be transmitted with a default number of data streams. STA 1002may indicate baseband/digital spatial schemes used for ACK frame (e.g.,ACK frame 1018 and/or 1024), such as STBC, SFBC, CSD, open loopprecoding, close loop precoding, and/or antenna/polarization selection.STA 1002 may indicate modulation and coding schemes for the ACK frame(e.g., ACK frame 1018 and/or 1024). The indication of the modulation andcoding schemes for the ACK frame may be omitted when the ACK frame maybe transmitted with a default MCS level. STA 1002 may indicate whetherthe ACK frame is poll based. If so, STA 1002 may indicate whether an(e.g., the first) ACK frame may be polled by STA 1002. The STAs (e.g.,STAs 1014 and 1020) may be ordered such that the ACK frames may betransmitted in different time slot using the order.

In the MU-MIMO setup implementation, STA 1014 may prepare the receptionof the MIMO setup frame 1004 using a default beam mode. On reception ofthe MIMO setup frame 1004, STA 1014 may gain the knowledge (e.g.,notice) that STA 1014 may be the first user to transmit the responseframe with or without polling. STA 1014 may transmit a response frame1016 to STA 1002 using a default beam mode and/or a beam mode assignedby STA 1002 in the MIMO setup frame 1004. The response frame 1016 maycarry information to indicate that STA 1014 may be ready for thefollowing MU-MIMO mode with beam/antenna allocation indicated by STA1002.

In the MU-MIMO setup implementation, on reception of the response frame1016 from STA 1014, STA 1002 may poll STA 1020. STA 1020 may prepare thereception of the MIMO setup frame 1004 and the poll frame 1006 using adefault beam mode. On reception of the MIMO setup frame 1004, the STA1020 may gain knowledge (e.g., notice) that the STA 1020 may be thesecond user to transmit the response frame 1022 with or without polling.On reception of the poll frame 1012, the STA 1020 may transmit theresponse frame 1022 to STA 1002 using a default beam mode or a beam modeassigned by STA 1002 in the MIMO setup frame 1004. The response frame1022 may carry information to indicate STA 1020 may be ready for thefollowing MU-MIMO mode with beam/antenna allocation indicated by STA1002.

In some cases of the MU-MIMO setup implementation, STA 1002 maysuccessfully receive response frames 1016 and 1022 from STA 1014 and STA1020, respectively. STA 1002 may transmit MU-MIMO PPDUs to STA 1014 andSTA 1020 as planed using signaled beam modes.

In some cases of the MU-MIMO setup implementation, STA 1002 maysuccessfully receive response frames from some of stations (e.g., thedesired users or stations associated with the users). STA 1002 may notsuccessfully receive response frames from all of the desired users. Inthis example, STA 1002 may receive (e.g., only receive) response framesfrom STA 1014. STA 1002 may use one or more of partial transmissionfailure scheme (e.g., as illustrated in FIG. 10B) or transmissionfailure scheme (e.g., as illustrated in FIG. 10C). For the partialtransmission failure scheme (e.g., as illustrated in FIG. 10B), variousapproaches may be used. In one of the approaches, STA 1002 may transmita MIMO end frame 1026 using the beam mode for STA 1014. xIFS periodlater, STA 1002 may transmit another MIMO end frame 1028 using defaultmode or quasi-omni mode to terminate the current MU-MIMO transmissionopportunity (TXOP) as shown in FIG. 10B. In one of the approaches, STA1014 may reply an ACK frame for the directional MIMO end frame 1026transmission. STA 1002 may transmit the MIMO end frame 1028, e.g., xIFSafter. In one of the approaches, the quasi-omni MIMO end frame 1028 maybe omitted.

In the transmission failure scheme (e.g., as illustrated in FIG. 10C),STA 1002 may continue the transmission (e.g., MU-MIMO transmission1030). STA 1002 may use (e.g., only use) the beams/antennas pointing toSTA 1014. STA 1002 may allocate a power (e.g., full power) to a subsetof users (e.g., STA 1014). STA 1014 may respond with an ACK frame 1032,as shown in FIG. 10C.

In some cases of the MU-MIMO setup implementation, STA 1002 may notreceive a (e.g., any) response frame from potential MU-MIMO users orstations associated with users (e.g., all of the users or stations). STA1002 may terminate the MU-MIMO TXOP by transmitting a MIMO end frame.

SU-MIMO setup implementations may be provided. SU-MIMO setupimplementation may be shown in FIG. 11. The scheme may be considered asan example MU-MIMO setup with a (e.g., one) user. As shown in exampleFIG. 11, STA 1110 (for example, an AP/PCP) may transmit a MU-MIMO setupframe 1102. The MU-MIMO setup frame 1102 may be transmitted in a defaultmulticast control frame transmission mode, e.g., basic quasi-omni modeor quasi-omni mode for single data stream transmission in type I or Kquasi-omni beams in type II beam modes. STA 1112 may prepare thereception of MIMO setup frame 1102 using a default beam mode. Onreception of the response frame 1106 from STA 1112, STA 1110 maytransmit MU-MIMO 1104 and receive an ACK frame 1108.

Training/tracking may be performed as part of and/or with the MIMO setupimplementation. An MIMO setup frame may be appended with a soundingsequence (e.g., an extra sounding sequence). For example, the MIMO setupimplementation may be for channel access with an MIMO setup frame(s).The training/tracking may include extra training/tracking. The extratraining/tracking may provide for additional training. Theimplementation herein may be applied to SU-MIMO and/or MU-MIMO.

As an example, the sounding sequence may be used for baseband/digitalBF/MIMO mode adaptation/selection. For example, the MIMO setup frame maybe transmitted using quasi-omni mode with a single data stream(s). TheCEF field(s) (including L-CEF and EDMG-CEF field) may be designed and/orused for single-data-stream estimation. TXOP holder/an initiator of theMIMO transmission may want to know full information or partialinformation about an effective MIMO channel after analog beamforming.The TXOP holder/the initiator of the MIMO transmission may gain the fullinformation or partial information about the effective MIMO channel,e.g., by appending extra known training sequences at the end of the PPDUtransmission. Tx and/or Rx may use a trained analog beam(s). A responder(e.g., a receiver such as a station) may use training sequences (e.g.,the extra known training sequences) to estimate the baseband MIMOchannel and/or feed back information requested by the initiator (e.g., atransmitter such as an AP). With the information fed back, the initiatormay decide the baseband/digital MIMO/BF mode. The MIMO response framemay be used to carry baseband channel-state information (CSI) feedback.Baseband BF/MIMO training may be combined with the MIMO setupimplementations and/or improve system efficiency.

As an example of MIMO setup implementations along with extratraining/tracking, the sounding sequence (e.g., the extra soundingsequence) may be used for analog beam tracking/refinement. For example,the MIMO setup frame may be transmitted using quasi-omni mode withsingle-data streams. The CEF field(s) (including L-CEF and EDMG-CEFfield) may be designed and/or used for single-data-stream estimation.The TXOP holder/the initiator may be aware that the transmit beam(s) orthe receive beam(s) or both may not be good enough. For example, atransmission(s) via the transmit beam(s) or the receive beam(s) or bothmay not meet certain quality criterion. The TXOP holder/the initiatormay decide to perform beam tracking/refinement during the MIMO setupimplementation. The extra training sequences may be used to transmitbeam training, receive beam training or transmit/receive beam training.The responder (e.g., the receiver such as a station) may use the extratraining sequences to determine the good beam(s) and/or bad beam(s) forthe transmitter and/or the receiver. With the determination of the goodbeam(s) and/or bad beam(s), the initiator (e.g., a transmitter such asan AP) and the responder (e.g., the receiver such as a station) mayupdate the analog beams. An example of MIMO setup implementation withextra training may be described herein (e.g., as shown in FIG. 12). Theexample of MIMO setup implementation with extra training may compriseone or more of the following.

As shown in FIG. 12, the example of MIMO setup implementation with extratraining may comprise that STA 1220 (e.g., an AP/PCP) may transmit aMIMO setup frame 1204 (e.g., a MU-MIMO setup frame or a SU-MIMO setupframe). The transmission of the MIMO setup frame 1204 may comprise aPLCP header 1202. An extra training field may carry multiple trainingsequences (e.g., training sequence 1206, training sequence 1208, and/ortraining sequence 1212). The training sequences may be transmitted usingdifferent antenna/beam patterns. The training sequences may be repeatedand/or transmitted using an antenna pattern (e.g., a fixed antenna/beampattern). A receiver(s) may sweep the receiver's antenna/beam pattern totrain one or more reception beams. A length of a training field (e.g.,the extra training field) may extend from the PLCP header 1202 or a partof the PLCP header 1202 to the end of a training sequence (e.g., thetraining sequence 1208). A purpose of the training and/or the feedbackrequest may be carried in MAC body of MIMO setup frame. In anotherembodiment, the purpose of the training and/or the feedback request maybe carried in the PLCP header. As an example, the frame 1204 may betransmitted using legacy DMG PPDU. The header field may be detected bythe legacy users. A quasi-omni antenna pattern may be used from thestarting of a packet to the end of a training sequence. A packet typefield in a header may be used to indicate that a packet may be appendedwith a TRN field (e.g., the TRN field may be appended after the dataportion). A value of N in the training length field may indicate thelength of the TRN field 1224. As an example, the frame may betransmitted using EDMG SU PPDU format. For example, EDGM-Header-B fieldmay not be present in the preamble. In legacy header (L-header) field, apacket type and/or training length field may be set to indicate thepresence of TRN-T field at the end of the packet. L-STF, L-LTF, L-Headerand/or EDMG-Header-A fields may be transmitted using a (e.g., a single)RF chain. L-STF, L-LTF, L-Header and/or EDMG-Header-A fields may betransmitted using some or all of the RF chains. Transmission techniques(e.g., described herein) may be used.

As an example, the PLCP header 1204 may comprise an L-header. In theL-header, A packet type field may be used to indicate that the packetmay be appended with a TRN field (e.g., the TRN field may be appendedafter the data portion). A value of N in a training length field mayindicate the length of the TRN field.

As an example of the PLCP header 1204, an EDMG-Header-A may be used. Inthe EDMG-Header-A, the EDMG-Header-A may indicate/comprise a useimmediately field. The use immediately field may be used to indicatewhether the MIMO transmission (e.g., the MIMO transmission right afterthe MIMO setup exchanges) may use the updated analog/baseband beams orschemes, for example, the updated analog/baseband beams or schemes thatare derived from the training using the extra training field appendedafter MIMO setup frame. The Use Immediately field may be set to 0, e.g.,in the case the transmitter/receiver may not have enough time to use theupdated beams or schemes. The training results may be used in latertransmissions.

The EDMG-Header-A may indicate/comprise the purpose of the extratraining field (e.g., EDMG-Header-A). The purpose of the extra trainingfield may include baseband MIMO channel sounding, analog beamtracking/refinement, and/or the like. When used for analog beamtracking/refinement, the extra training filed may be used for Txtraining (e.g., Tx training only) such as Tx sweeping and/or trainingdifferent beams. The extra training filed may be used for Rx training(e.g., Rx training only). Tx beams may be used (e.g., fixed) and/orrepeated for a certain length, which allows the Rx to sweep the Rx'sbeams. When used for analog beam tracking/refinement, the extra trainingfiled may be used for a combination of Tx and Rx training. The order inwhich Tx and/or Rx training may be specified. For example, the Txtraining may be performed first and then Rx training. The Rx trainingmay be performed first and followed by the Tx training. The number ofTx/Rx training may be specified, e.g., if an unequal number of Tx/Rxtraining may be applied. For example, N1 sequences for Tx training andfollowed by N2 sequences for Rx training.

The EDMG-Header-A may indicate/comprise feedback type. The feedback typemay comprise a limited channel state information feedback, such asaverage SNR/SINR feedback per Tx/Rx antenna pair. For example, STA 1220may request average SNR or SINR feedback when STA 1220 plans to performbaseband/digital domain transmit/receive beam/polarization selection.The feedback type may comprise a full channel state information feedbackper Tx/Rx antenna pair. For example, STA 1220 may request a full CSIfeedback when STA 1220 plans to perform close loop precoding.

The EDMG-Header-A may indicate/comprise channel feedback resolution(e.g., a channel feedback resolution per Tx/Rx antenna pair). Thechannel feedback resolution may indicate a quantitation level of thefeedback. For example, the channel feedback resolution may indicate(e.g., define) the number of bits that represents a real/complex valuedepending on the feedback type. The real/complex value may be anSNR/SINR value, or an average of SNR/SINR values. The real/complex valuemay comprise a delay, a time domain tap strength, a time domain tapphase, and/or the like.

The transmission of MIMO setup frame may comprise a MAC packet. The MACpacket may comprise an EDMG MAC packet. In some scenarios, e.g., the MACpacket may be carried by a DMG PPDU. The EDMG MAC packet may bepartially understood by legacy users. The EDMG MAC packet may carry MIMOsetup information (e.g., as described herein). The EDMG MAC packet maycarry information about baseband BF training setting requirements. Theinformation about baseband BF training setting requirements may includeuse immediately field. The use immediately field may be the same as usedin EDMG-Header-A field. The information about baseband BF trainingsetting requirements including a use immediately field information maybe carried in a PLCP header and/or an MAC packet. The information aboutbaseband BF training setting requirements may include a purpose of theextra training field. The field indicating the purpose of the extratraining field (e.g., together with other fields) may be carried in aEDMG-Header-A field and/or MAC body.

The use immediately field may indicate/comprise channel feedbackresolution (e.g., a channel feedback resolution per Tx/Rx antenna pair).The channel feedback resolution may indicate a quantitation level of thefeedback. For example, the channel feedback resolution may indicate(e.g., define) the number of bits that represents a real/complex valuedepending on the feedback type. The real/complex value may be anSNR/SINR value, or an average of SNR/SINR values. The real/complex valuemay comprise a delay, a time domain tap strength, a time domain tapphase, and/or the like.

The information about baseband BF training setting requirementsincluding the purpose of the extra training field may be carried in aPLCP header and/or am MAC packet. The information about baseband BFtraining setting requirements may include channel feedback type. Thefeedback type may be the same as used in EDMG-Header-A field. Thechannel feedback type may indicate/comprise channel feedback resolution(e.g., a channel feedback resolution per Tx/Rx antenna pair). Thechannel feedback resolution may indicate a quantitation level of thefeedback. For example, the channel feedback resolution may indicate(e.g., define) the number of bits that represents a real/complex valuedepending on the feedback type. The real/complex value may be anSNR/SINR value, or an average of SNR/SINR values. The real/complex valuemay comprise a delay, a time domain tap strength, a time domain tapphase, and/or the like.

The information about baseband BF training setting requirementsincluding channel feedback type information may be carried in PLCPheader and/or MAC packet. The information about baseband BF trainingsetting requirements may comprise channel feedback resolution per Tx/Rxantenna pair. This field may be the same as used in EDMG-Header-A field.The channel feedback resolution per Tx/Rx antenna pair mayindicate/comprise channel feedback resolution (e.g., a channel feedbackresolution per Tx/Rx antenna pair). The channel feedback resolution mayindicate a quantitation level of the feedback. For example, the channelfeedback resolution may indicate (e.g., define) the number of bits thatrepresents a real/complex value depending on the feedback type. Thereal/complex value may be an SNR/SINR value, or an average of SNR/SINRvalues. The real/complex value may comprise a delay, a time domain tapstrength, a time domain tap phase, and/or the like. The informationabout baseband BF training setting requirements including channelfeedback resolution per Tx/Rx antenna pair may be carried in PLCP headerand/or MAC packet.

The transmission of MIMO setup frame may comprise training sequences(e.g., extra training field). In the extra training field, STA 1220 maytransmit training sequences, e.g., using the antennas and beams to betrained. As an example, the extra training field may be appended rightafter the MAC packet. In one or more of the examples herein, in order togive beamformee(s) (e.g., STA 1222 in this example) more processing timeto acquire the TX antennas and beams to be used, the extra trainingfield may be transmitted xIFS time after the end of the EDMG MAC packettransmission.

The example of MIMO setup implementation with extra training maycomprise that STA 1222 may transmit a response frame 1210. STA 1222 maycarry the feedback information requested by STA 1220 (e.g., in theresponse frame 1210). STA 1222 may perform according to a MIMO setupimplementation (e.g., the MIMO setup implementation described herein).STA 1222 may send an ACK/BA 1218. The TX/RX antenna may be set back todefault mode.

The example of MIMO setup implementation with extra training maycomprise that STA 1220 may perform a MIMO transmission 1216 using theinformation updated by the feedback e.g., if use Immediately field isset. STA 1220 may use the beams and/or transmission schemes signaled(e.g., explicitly signaled) by the MIMO setup frame 1204.

In the example of MIMO setup implementation with extra training, theextra training field may be appended to the MIMO setup frame. Theexample of MIMO setup implementation with extra training may be extendedto more general cases. For example, in any beam refinement protocol(BRP) or extended BRP frame, an extra training field(s) may be appendedfor a same or similar purpose, e.g., the baseband full/partial CSIsounding, the analog beam tracking/refinement etc. The signalingdescribed here may be carried in one or more of the PLCP header of theBRP or eBRP frame, BRP or eBRP MAC packet, or MAC header.

MIMO setup frames may include various fields. An MIMO setup frame mayinclude a common field and/or a user specific field. With SU-MIMO setup,a (e.g., one) user specific field may be present. The MIMO setup framemay include one or more fields indicating one or more of a Tx/Rx ID, Nssexpected for a (e.g., each) user in the following MIMO datatransmission, analog beam pattern to be used in the MIMO transmission,baseband MIMO type to be used in the MIMO transmission, setting up theresponse frames expected from the STA(s), and/or other information ifextra training fields are appended. The field used to indicate analogbeam pattern to be used in MIMO transmission may indicate or include oneor more PAA information/index, polarization information/index, analogbeam index, or other beam candidates. The field used to indicatebaseband MIMO type to be used in MIMO transmission may indicate orcomprise one or more of antenna/PAA/polarization selection, selectedindices, STBC like scheme (e.g., a SFBC), dual carrier modulation orspatial/frequency/time domain dual carrier modulation, or close loop(CL) precoding, or open loop (OL) precoding. The selected indices may besignaled, e.g., before MIMO transmission. The field used to set up theresponse frames expected from the STA(s) may indicate or comprise one ormore response frames for an MIMO setup frame, or an ACK frame for MIMOtransmission. Other information if extra training fields may be appendedmay indicate or comprise one or more use immediately field, a purpose ofthe extra training field, channel feedback type, or channel feedbackresolution.

When multiple streams that comprise a same legacy fields (e.g., legacyShort Training Field (STF), channel estimation field (CEF), and Header)are transmitted from multiple antennas, unintentional beamforming mayoccur on the received signal due to a strong correlation betweentransmitted signals. A variation of received signal power may causesuboptimal AGC setting to decode a legacy header at legacy devices.Different cyclic shift may be applied to a transmitted signal, forexample, to decorrelate the transmit signals. An operation of applyingdifferent cyclic shift to a transmitted signal may be compatible withcyclic prefix (CP)-OFDM transmissions.

MIMO transmission implementations for preamble may be used, for exampleto reduce unintentional beamforming. Several techniques may be providedfor single carrier waveforms such as linear shifts and block-basedcircular shifts. A choice of techniques (e.g., as shown in FIG. 13A-13C)may enable interference-free channel estimation for a legacy device.

For example, for linear shifts, the transmitter may intentionally shiftthe spatial streams transmitted through different antennas. Singlecarrier waveforms (e.g., upon linear shifting) may not be aligned at thereceiver and/or may avoid unintentional beamforming. The transmitter mayapply block-based circular shifts. For example, the legacy fields of thePPDU may be circularly shifted. One or more legacy fields (e.g., asdescribed herein) may be or include pre-EDMG modulated fields. Thepre-EDMG modulated fields may include legacy STF field, legacy CEFfields and headers. A circular shift may be applied to STF, CEF, and/orheader that are grouped. In one or more examples herein, the circularshift may be applied to specific group of fields or subfields (e.g.,particular Golay sequences). For instance, as illustrated in FIG. 13,spatial stream 1326 may include a short training field 1302, a channelestimation field 1306, a header 1308, and other 11ay fields 1310.Spatial stream 1328 may include a short training field 1312, a channelestimation field 1314, a header 1316 and other 11ay fields 1318. Spatialstream 1328 may include a short training field 1312, a channelestimation field 1314, a header 1316, and other 11ay fields 1318.Spatial stream 1330 may include a short training field 1319, a channelestimation field 1320, a header 1322, and other 11ay fields 1324. FIG.13A may show an example of the linear shift. The spatial stream 1326 mayhave been linearly shifted from the spatial stream 1328 (e.g., shown in1332). The spatial stream 1328 may have been linearly shifted from thespatial stream 1330 (e.g., shown in 1334).

The transmitter may apply block-based circular shifts. For example,legacy fields of the PPDU may be circularly shifted. STF, CEF, and/orheader may be grouped, and/or a circular shift may be applied to thegroup. A circular shift may be applied to STF, CEF, and/or header thatare grouped. In one or more examples herein, the circular shift may beapplied to a selected (e.g., a specific) group of fields or subfields(e.g., Golay sequences). The grouping may consider one or more of aSTF(s) excluding the Golay sequence (e.g., −Ga128) in the end of theSTF(s), a CEF(s) including the Golay sequence (e.g., −Ga128) in the endof the STF(s), or a header. As shown in FIG. 13B, the grouping mayconsider a STF(s) excluding the Golay sequence (e.g., −Ga128) in the endof the STF(s). For spatial stream 1328, the block shift of the STF(s)excluding the Golay sequence (e.g., −Ga128) in the end of the STF(s) maybe shown in the block circular shifts 1332. For spatial stream 1330, theblock shift of the STF(s) excluding the Golay sequence (e.g., −Ga128) inthe end of the STF(s) may be shown in the block circular shifts 1338. Asshown in FIG. 13B, the grouping may consider a CEF(s) including theGolay sequence (e.g., −Ga128) in the end of the STF(s). For spatialstream 1328, the block shift of the a CEF(s) including the Golaysequence (e.g., −Ga128) in the end of the STF(s) may be shown in theblock circular shifts 1334. For spatial stream 1330, the block shift ofthe a CEF(s) including the Golay sequence (e.g., −Ga128) in the end ofthe STF(s) may be shown in the block circular shifts 1340. As shown inFIG. 13B, the grouping may consider a header. For spatial stream 1328,the block shift of the header may be shown in the block circular shifts1336. For spatial stream 1330, the block shift of the header may beshown in the block circular shifts 1342.

The block-based shift may consider subfields and purposes of thesubfields. FIG. 13C may show an example of the block-based shiftconsidering the purposes of the subfields. For spatial stream 1328, theblock shifts 1344 may consider the purposes of the subfields 1312-1316.For spatial stream 1330, the block shifts 1346 may consider the purposesof the subfields 1319-1322. A choice of techniques for avoidingunintentional beamforming block-based shift (e.g., as shown in FIG. 15B)may enable interference-free channel estimation for the legacy device.

Circular CEFs may be used for multiple streams (e.g., stream 1402 andstream 1404). In IEEE 802.11ad, the sequence in the CEF may introduce aproperty zero autocorrelation zone, which may enable the channelestimation in time domain via correlation operations as illustrated inFIG. 14. As shown in FIG. 14, two streams, stream 1402 and stream 1404may share a zero correlation zone 1420. Stream 1404 may include a shorttraining field 1422, a channel estimation filed 1424, and a −Gb128 1412.The −Gb128 1412 may be used as a guard. The short training field 1422may include a number of −Ga128 including −Ga128 1406. The channelestimation filed 1424 may include a number of Ga128 s and −Gb128 s(e.g., Gb128 1416). Stream 1404 may include the zero autocorrelationzone 1420. Stream 1402 may include a number of Ga128 and −Gb128 (e.g.,−Gb128 1408) including the number of Ga128 s and −Gb128 included in thezero autocorrelation zone 1420. The zero autocorrelation zone 1420 mayinclude Ga128 1410. Stream 1402 may lag stream 1404, as shown in the lag1414.

As shown in graph 1426, the x axis refers to the lag, and the y axisrefers to energy. In an embodiment, y axis may refer to correlation.Along x-axis between stream 1402 and stream 1404, the energy remains low(e.g., towards or at zero energy), indicating a zero autocorrelationzone 1428.

As an example, the zero correlation zone (e.g., 1506 for stream 1502 and1516 for stream 1504)) may be shared with more than one streams (e.g.,stream 1502 and stream 1504) to enable channel estimation for differentstreams (e.g., stream 1502 and stream 1504). For example, two orthogonalCEFs may be generated by circularly shifting the original CEF of802.11ad or any other sequence with zero autocorrelation zone includingthe sequence with full zero autocorrelation zone (e.g., Zadoff-chusequence). The orthogonal CEFs may be generated if the shifts (e.g.,circuit shift 1510 and 1512) are by −64 and +64 at least as illustratedin FIG. 15A. FIG. 15B may show various auto/cross correlation results,for example, based on the implementation from FIG. 15A.

Since sequences 1502 and 1504 are derived from the original sequences1402 and 1404 by using circular or linear shifts, the sequences 1502 and1504 may maintain the same zero auto-correlation zone as shown in FIG.14. For example, the zero auto-correlation zone 1420 is the same as thezero auto-correlation zone 1506. The sequences 1502 and 1504 may bemutually orthogonal to each other (e.g., +−64 sample shifts). Similartechniques may be extended to multibeam training purposes, e.g., byintroducing smaller circular shift values.

A step-wise implementation may be used for multi-stream support.Multiple STAs, for example, a pair of STAs, e.g., an EDMG AP/PCP and aEDMG STA, or two EDMG STAs. A step-wise implementation may be used toestablish transmission and/or reception of multiple data streams amongthem. The pair of STAs may include an EDMG AP/PCP and a EDMG STA, or twoEDMG STAs. An example of the step-wise implementation may include one ormore of the following.

The step-wise implementation may comprise a STA, e.g., an EDMG AP/PCP oran EDMG STA, that may use a quasi-omni beam to conduct initialtransmissions with another STA.

The step-wise implementation may comprise that, after the initialquasi-omni transmissions, the STA pair may proceed to conduct beamtraining, e.g., using SLS or BRP. During the SLR and BRP, one or more TXSectors and/or one or more of RX Sectors may be selected. If the STAsare equipped with multiple PAAs, the STAs may conduct SLS and/or BRPconcurrently using different PAAs. The SLS and/or BRP patterns may besuch that the different PAAs on the transmitting STA may not overlap inbeam (e.g., a coverage of the beam(s) may not be overlapped) and thedifferent PAAs on the receiving STA may not overlap in beam. DifferentPAAs on the transmitting STA may transmit using orthogonal signaling,such as using orthogonal codes or set of subcarriers. The orthogonalsignaling may carry identifications of the different PAAs. The receivingSTA may use a different PAA to decode the orthogonal signaling, and/oridentifying from which transmitting PAA from which the received signalis received. Using the concurrent transmission and/or reception amongmultiple PAAs, multiple (e.g., the pair of) STAs may select one or moreTx Sectors and one or more Rx Sectors, which may be associated with oneor more PAAs on the transmitting and receiving STAs. The set of Txsectors and Rx sectors, which may be associated with multiple PAAs, maybe used to establish MIMO transmissions among multiple (e.g., betweenthe pair of the STAs).

The step-wise implementation may comprise that, if one or more Txsectors and Rx sectors are selected, which may be associated withdifferent PAAs on the pair of the STAs, a STA (e.g., one of the STAs),for example an EDMG AP/PCP or EDMG STA, may request higher number ofdata streams. For one or more Tx/Rx sector pairs, the STA may requestpolarization training, for example, in order to transmit higher numberof streams using the one or more Tx/Rx sector pair. The requestingSTA(s) may indicate requested polarization type, such as circular,linear, mixed, vertical, horizontal. The requesting STA(s) may expressthe requested polarization type, for example, using Euler angle relativeto a (e.g., an existing) polarization or to a coordination system. Therequesting STA (e.g., a transmitter such as an AP) and the respondingSTA (e.g., a receiver such as a STA) may conduct polarization trainingfor the requested polarization type. The responding STA may providefeedback for the polarization training. The requesting STA may requestpolarization mode change. The requesting STA may request thepolarization mode change by adding additional streams. The additionalstreams may be transmitted using a different polarization type, forexample to provide higher number of data streams using the same Tx/Rxsector pair.

The step-wise implementation may comprise that, if a requesting STA useshigher/lower data rate, the requesting STA may request to use wider ornarrow channel bands, for example, more or less subcarriers. If theresponding STA is capable of wider channel transmissions, the respondingSTA may respond affirmatively. Multiple STAs (e.g., the pair of STAs)may use wider or narrow channel for one or more of Tx/Rx sectorssubsequently.

Although the features and elements of the present invention aredescribed in the preferred embodiments in particular combinations, eachfeature or element can be used alone without the other features andelements of the preferred embodiments or in various combinations with orwithout other features and elements of the present invention. Althoughthe solutions described herein consider 802.11 specific protocols, it isunderstood that the solutions described herein are not restricted tothis scenario and are applicable to other wireless systems.

FIG. 16A illustrates exemplary wireless local area network (WLAN)devices. One or more of the devices may be used to implement one or moreof the features described herein. The WLAN may include, but is notlimited to, access point (AP) 102, station (STA) 110, and STA 112. STA110 and 112 may be associated with AP 102. The WLAN may be configured toimplement one or more protocols of the IEEE 802.11 communicationstandard, which may include a channel access scheme, such as DSSS, OFDM,OFDMA, etc. A WLAN may operate in a mode, e.g., an infrastructure mode,an ad-hoc mode, etc.

A WLAN operating in an infrastructure mode may comprise one or more APscommunicating with one or more associated STAs. An AP and STA(s)associated with the AP may comprise a basic service set (BSS). Forexample, AP 102, STA 110, and STA 112 may comprise BSS 122. An extendedservice set (ESS) may comprise one or more APs (with one or more BSSs)and STA(s) associated with the APs. An AP may have access to, and/orinterface to, distribution system (DS) 116, which may be wired and/orwireless and may carry traffic to and/or from the AP. Traffic to a STAin the WLAN originating from outside the WLAN may be received at an APin the WLAN, which may send the traffic to the STA in the WLAN. Trafficoriginating from a STA in the WLAN to a destination outside the WLAN,e.g., to server 118, may be sent to an AP in the WLAN, which may sendthe traffic to the destination, e.g., via DS 116 to network 114 to besent to server 118. Traffic between STAs within the WLAN may be sentthrough one or more APs. For example, a source STA (e.g., STA 110) mayhave traffic intended for a destination STA (e.g., STA 112). STA 110 maysend the traffic to AP 102, and, AP 102 may send the traffic to STA 112.

A WLAN may operate in an ad-hoc mode. The ad-hoc mode WLAN may bereferred to as independent basic service set (IBBS). In an ad-hoc modeWLAN, the STAs may communicate directly with each other (e.g., STA 110may communicate with STA 112 without such communication being routedthrough an AP).

IEEE 802.11 devices (e.g., IEEE 802.11 APs in a BSS) may use beaconframes to announce the existence of a WLAN network. An AP, such as AP102, may transmit a beacon on a channel, e.g., a fixed channel, such asa primary channel. A STA may use a channel, such as the primary channel,to establish a connection with an AP.

STA(s) and/or AP(s) may use a Carrier Sense Multiple Access withCollision Avoidance (CSMA/CA) channel access mechanism. In CSMA/CA a STAand/or an AP may sense the primary channel. For example, if a STA hasdata to send, the STA may sense the primary channel. If the primarychannel is detected to be busy, the STA may back off. For example, aWLAN or portion thereof may be configured so that one STA may transmitat a given time, e.g., in a given BSS. Channel access may include RTSand/or CTS signaling. For example, an exchange of a request to send(RTS) frame may be transmitted by a sending device and a clear to send(CTS) frame that may be sent by a receiving device. For example, if anAP has data to send to a STA, the AP may send an RTS frame to the STA.If the STA is ready to receive data, the STA may respond with a CTSframe. The CTS frame may include a time value that may alert other STAsto hold off from accessing the medium while the AP initiating the RTSmay transmit its data. On receiving the CTS frame from the STA, the APmay send the data to the STA.

A device may reserve spectrum via a network allocation vector (NAV)field. For example, in an IEEE 802.11 frame, the NAV field may be usedto reserve a channel for a time period. A STA that wants to transmitdata may set the NAV to the time for which it may expect to use thechannel. When a STA sets the NAV, the NAV may be set for an associatedWLAN or subset thereof (e.g., a BSS). Other STAs may count down the NAVto zero. When the counter reaches a value of zero, the NAV functionalitymay indicate to the other STA that the channel is now available.

The devices in a WLAN, such as an AP or STA, may include one or more ofthe following: a processor, a memory, a radio receiver and/ortransmitter (e.g., which may be combined in a transceiver), one or moreantennas (e.g., antennas 106 in FIG. 16A), etc. A processor function maycomprise one or more processors. For example, the processor may compriseone or more of: a general purpose processor, a special purpose processor(e.g., a baseband processor, a MAC processor, etc.), a digital signalprocessor (DSP), Application Specific Integrated Circuits (ASICs), FieldProgrammable Gate Array (FPGAs) circuits, any other type of integratedcircuit (IC), a state machine, and the like. The one or more processorsmay be integrated or not integrated with each other. The processor(e.g., the one or more processors or a subset thereof) may be integratedwith one or more other functions (e.g., other functions such as memory).The processor may perform signal coding, data processing, power control,input/output processing, modulation, demodulation, and/or any otherfunctionality that may enable the device to operate in a wirelessenvironment, such as the WLAN of FIG. 16A. The processor may beconfigured to execute processor executable code (e.g., instructions)including, for example, software and/or firmware instructions. Forexample, the processer may be configured to execute computer readableinstructions included on one or more of the processor (e.g., a chipsetthat includes memory and a processor) or memory. Execution of theinstructions may cause the device to perform one or more of thefunctions described herein.

A device may include one or more antennas. The device may employmultiple input multiple output (MIMO) techniques. The one or moreantennas may receive a radio signal. The processor may receive the radiosignal, e.g., via the one or more antennas. The one or more antennas maytransmit a radio signal (e.g., based on a signal sent from theprocessor).

The device may have a memory that may include one or more devices forstoring programming and/or data, such as processor executable code orinstructions (e.g., software, firmware, etc.), electronic data,databases, or other digital information. The memory may include one ormore memory units. One or more memory units may be integrated with oneor more other functions (e.g., other functions included in the device,such as the processor). The memory may include a read-only memory (ROM)(e.g., erasable programmable read only memory (EPROM), electricallyerasable programmable read only memory (EEPROM), etc.), random accessmemory (RAM), magnetic disk storage media, optical storage media, flashmemory devices, and/or other non-transitory computer-readable media forstoring information. The memory may be coupled to the processer. Theprocesser may communicate with one or more entities of memory, e.g., viaa system bus, directly, etc.

FIG. 16B is a diagram of an example communications system 100 in whichone or more disclosed features may be implemented. For example, awireless network (e.g., a wireless network comprising one or morecomponents of the communications system 100) may be configured such thatbearers that extend beyond the wireless network (e.g., beyond a walledgarden associated with the wireless network) may be assigned QoScharacteristics.

The communications system 100 may be a multiple access system thatprovides content, such as voice, data, video, messaging, broadcast,etc., to multiple wireless users. The communications system 100 mayenable multiple wireless users to access such content through thesharing of system resources, including wireless bandwidth. For example,the communications systems 100 may employ one or more channel accessmethods, such as code division multiple access (CDMA), time divisionmultiple access (TDMA), frequency division multiple access (FDMA),orthogonal FDMA (OFDMA), single-carrier FDMA (SC-FDMA), and the like.

As shown in FIG. 16B, the communications system 100 may include at leastone wireless transmit/receive unit (WTRU), such as a plurality of WTRUs,for instance WTRUs 102 a, 102 b, 102 c, and 102 d, a radio accessnetwork (RAN) 104, a core network 106, a public switched telephonenetwork (PSTN) 108, the Internet 110, and other networks 112, though itshould be appreciated that the disclosed embodiments contemplate anynumber of WTRUs, base stations, networks, and/or network elements. Eachof the WTRUs 102 a, 102 b, 102 c, 102 d may be any type of deviceconfigured to operate and/or communicate in a wireless environment. Byway of example, the WTRUs 102 a, 102 b, 102 c, 102 d may be configuredto transmit and/or receive wireless signals and may include userequipment (UE), a mobile station (e.g., a WLAN STA), a fixed or mobilesubscriber unit, a pager, a cellular telephone, a personal digitalassistant (PDA), a smartphone, a laptop, a netbook, a personal computer,a wireless sensor, consumer electronics, and the like.

The communications systems 100 may also include a base station 114 a anda base station 114 b. Each of the base stations 114 a, 114 b may be anytype of device configured to wirelessly interface with at least one ofthe WTRUs 102 a, 102 b, 102 c, 102 d to facilitate access to one or morecommunication networks, such as the core network 106, the Internet 110,and/or the networks 112. By way of example, the base stations 114 a, 114b may be a base transceiver station (BTS), a Node-B, an eNode B, a HomeNode B, a Home eNode B, a site controller, an access point (AP), awireless router, and the like. While the base stations 114 a, 114 b areeach depicted as a single element, it should be appreciated that thebase stations 114 a, 114 b may include any number of interconnected basestations and/or network elements.

The base station 114 a may be part of the RAN 104, which may alsoinclude other base stations and/or network elements (not shown), such asa base station controller (BSC), a radio network controller (RNC), relaynodes, etc. The base station 114 a and/or the base station 114 b may beconfigured to transmit and/or receive wireless signals within aparticular geographic region, which may be referred to as a cell (notshown). The cell may further be divided into cell sectors. For example,the cell associated with the base station 114 a may be divided intothree sectors. Thus, in one embodiment, the base station 114 a mayinclude three transceivers, i.e., one for each sector of the cell. Inanother embodiment, the base station 114 a may employ multiple-inputmultiple output (MIMO) technology and, therefore, may utilize multipletransceivers for each sector of the cell.

The base stations 114 a, 114 b may communicate with one or more of theWTRUs 102 a, 102 b, 102 c, 102 d over an air interface 116, which may beany suitable wireless communication link (e.g., radio frequency (RF),microwave, infrared (IR), ultraviolet (UV), visible light, etc.). Theair interface 116 may be established using any suitable radio accesstechnology (RAT).

More specifically, as noted above, the communications system 100 may bea multiple access system and may employ one or more channel accessschemes, such as CDMA, TDMA, FDMA, OFDMA, SC-FDMA, and the like. Forexample, the base station 114 a in the RAN 104 and the WTRUs 102 a, 102b, 102 c may implement a radio technology such as Universal MobileTelecommunications System (UMTS) Terrestrial Radio Access (UTRA), whichmay establish the air interface 116 using wideband CDMA (WCDMA). WCDMAmay include communication protocols such as High-Speed Packet Access(HSPA) and/or Evolved HSPA (HSPA+). HSPA may include High-Speed DownlinkPacket Access (HSDPA) and/or High-Speed Uplink Packet Access (HSUPA).

In another embodiment, the base station 114 a and the WTRUs 102 a, 102b, 102 c may implement a radio technology such as Evolved UMTSTerrestrial Radio Access (E-UTRA), which may establish the air interface116 using Long Term Evolution (LTE) and/or LTE-Advanced (LTE-A).

In other embodiments, the base station 114 a and the WTRUs 102 a, 102 b,102 c may implement radio technologies such as IEEE 802.16 (i.e.,Worldwide Interoperability for Microwave Access (WiMAX)), CDMA2000,CDMA2000 1X, CDMA2000 EV-DO, Interim Standard 2000 (IS-2000), InterimStandard 95 (IS-95), Interim Standard 856 (IS-856), Global System forMobile communications (GSM), Enhanced Data rates for GSM Evolution(EDGE), GSM EDGE (GERAN), and the like.

The base station 114 b in FIG. 16B may be a wireless router, Home NodeB, Home eNode B, or access point, for example, and may utilize anysuitable RAT for facilitating wireless connectivity in a localized area,such as a place of business, a home, a vehicle, a campus, and the like.In one embodiment, the base station 114 b and the WTRUs 102 c, 102 d mayimplement a radio technology such as IEEE 802.11 to establish a wirelesslocal area network (WLAN). In another embodiment, the base station 114 band the WTRUs 102 c, 102 d may implement a radio technology such as IEEE802.15 to establish a wireless personal area network (WPAN). In yetanother embodiment, the base station 114 b and the WTRUs 102 c, 102 dmay utilize a cellular-based RAT (e.g., WCDMA, CDMA2000, GSM, LTE,LTE-A, etc.) to establish a picocell or femtocell. As shown in FIG. 16B,the base station 114 b may have a direct connection to the Internet 110.Thus, the base station 114 b may not be required to access the Internet110 via the core network 106.

The RAN 104 may be in communication with the core network 106, which maybe any type of network configured to provide voice, data, applications,and/or voice over internet protocol (VoIP) services to one or more ofthe WTRUs 102 a, 102 b, 102 c, 102 d. For example, the core network 106may provide call control, billing services, mobile location-basedservices, pre-paid calling, Internet connectivity, video distribution,etc., and/or perform high-level security functions, such as userauthentication. Although not shown in FIG. 16B, it should be appreciatedthat the RAN 104 and/or the core network 106 may be in direct orindirect communication with other RANs that employ the same RAT as theRAN 104 or a different RAT. For example, in addition to being connectedto the RAN 104, which may be utilizing an E-UTRA radio technology, thecore network 106 may also be in communication with another RAN (notshown) employing a GSM radio technology.

The core network 106 may also serve as a gateway for the WTRUs 102 a,102 b, 102 c, 102 d to access the PSTN 108, the Internet 110, and/orother networks 112. The PSTN 108 may include circuit-switched telephonenetworks that provide plain old telephone service (POTS). The Internet110 may include a global system of interconnected computer networks anddevices that use common communication protocols, such as thetransmission control protocol (TCP), user datagram protocol (UDP) andthe internet protocol (IP) in the TCP/IP internet protocol suite. Thenetworks 112 may include wired or wireless communications networks ownedand/or operated by other service providers. For example, the networks112 may include another core network connected to one or more RANs,which may employ the same RAT as the RAN 104 or a different RAT.

Some or all of the WTRUs 102 a, 102 b, 102 c, 102 d in thecommunications system 100 may include multi-mode capabilities, i.e., theWTRUs 102 a, 102 b, 102 c, 102 d may include multiple transceivers forcommunicating with different wireless networks over different wirelesslinks. For example, the WTRU 102 c shown in FIG. 16B may be configuredto communicate with the base station 114 a, which may employ acellular-based radio technology, and with the base station 114 b, whichmay employ an IEEE 802 radio technology.

FIG. 16C depicts an exemplary wireless transmit/receive unit, WTRU 102.A WTRU may be a user equipment (UE), a mobile station, a WLAN STA, afixed or mobile subscriber unit, a pager, a cellular telephone, apersonal digital assistant (PDA), a smartphone, a laptop, a netbook, apersonal computer, a wireless sensor, consumer electronics, and thelike. WTRU 102 may be used in one or more of the communications systemsdescribed herein. As shown in FIG. 16C, the WTRU 102 may include aprocessor 118, a transceiver 120, a transmit/receive element 122, aspeaker/microphone 124, a keypad 126, a display/touchpad 128,non-removable memory 130, removable memory 132, a power source 134, aglobal positioning system (GPS) chipset 136, and other peripherals 138.It should be appreciated that the WTRU 102 may include anysub-combination of the foregoing elements while remaining consistentwith an embodiment.

The processor 118 may be a general purpose processor, a special purposeprocessor, a conventional processor, a digital signal processor (DSP), aplurality of microprocessors, one or more microprocessors in associationwith a DSP core, a controller, a microcontroller, Application SpecificIntegrated Circuits (ASICs), Field Programmable Gate Array (FPGAs)circuits, any other type of integrated circuit (IC), a state machine,and the like. The processor 118 may perform signal coding, dataprocessing, power control, input/output processing, and/or any otherfunctionality that enables the WTRU 102 to operate in a wirelessenvironment. The processor 118 may be coupled to the transceiver 120,which may be coupled to the transmit/receive element 122. While FIG. 16Cdepicts the processor 118 and the transceiver 120 as separatecomponents, it should be appreciated that the processor 118 and thetransceiver 120 may be integrated together in an electronic package orchip.

The transmit/receive element 122 may be configured to transmit signalsto, or receive signals from, a base station (e.g., the base station 114a) over the air interface 116. For example, in one embodiment, thetransmit/receive element 122 may be an antenna configured to transmitand/or receive RF signals. In another embodiment, the transmit/receiveelement 122 may be an emitter/detector configured to transmit and/orreceive IR, UV, or visible light signals, for example. In yet anotherembodiment, the transmit/receive element 122 may be configured totransmit and receive both RF and light signals. It should be appreciatedthat the transmit/receive element 122 may be configured to transmitand/or receive any combination of wireless signals.

In addition, although the transmit/receive element 122 is depicted inFIG. 16C as a single element, the WTRU 102 may include any number oftransmit/receive elements 122. More specifically, the WTRU 102 mayemploy MIMO technology. Thus, in one embodiment, the WTRU 102 mayinclude two or more transmit/receive elements 122 (e.g., multipleantennas) for transmitting and receiving wireless signals over the airinterface 116.

The transceiver 120 may be configured to modulate the signals that areto be transmitted by the transmit/receive element 122 and to demodulatethe signals that are received by the transmit/receive element 122. Asnoted above, the WTRU 102 may have multi-mode capabilities. Thus, thetransceiver 120 may include multiple transceivers for enabling the WTRU102 to communicate via multiple RATs, such as UTRA and IEEE 802.11, forexample.

The processor 118 of the WTRU 102 may be coupled to, and may receiveuser input data from, the speaker/microphone 124, the keypad 126, and/orthe display/touchpad 128 (e.g., a liquid crystal display (LCD) displayunit or organic light-emitting diode (OLED) display unit). The processor118 may also output user data to the speaker/microphone 124, the keypad126, and/or the display/touchpad 128. In addition, the processor 118 mayaccess information from, and store data in, any type of suitable memory,such as the non-removable memory 130 and/or the removable memory 132.The non-removable memory 130 may include random-access memory (RAM),read-only memory (ROM), a hard disk, or any other type of memory storagedevice. The removable memory 132 may include a subscriber identitymodule (SIM) card, a memory stick, a secure digital (SD) memory card,and the like. In other embodiments, the processor 118 may accessinformation from, and store data in, memory that is not physicallylocated on the WTRU 102, such as on a server or a home computer (notshown).

The processor 118 may receive power from the power source 134, and maybe configured to distribute and/or control the power to the othercomponents in the WTRU 102. The power source 134 may be any suitabledevice for powering the WTRU 102. For example, the power source 134 mayinclude one or more dry cell batteries (e.g., nickel-cadmium (NiCd),nickel-zinc (NiZn), nickel metal hydride (NiMH), lithium-ion (Li-ion),etc.), solar cells, fuel cells, and the like.

The processor 118 may also be coupled to the GPS chipset 136, which maybe configured to provide location information (e.g., longitude andlatitude) regarding the current location of the WTRU 102. In additionto, or in lieu of, the information from the GPS chipset 136, the WTRU102 may receive location information over the air interface 116 from abase station (e.g., base stations 114 a, 114 b) and/or determine itslocation based on the timing of the signals being received from two ormore nearby base stations. It should be appreciated that the WTRU 102may acquire location information by way of any suitablelocation-determination method while remaining consistent with anembodiment.

The processor 118 may further be coupled to other peripherals 138, whichmay include one or more software and/or hardware modules that provideadditional features, functionality and/or wired or wirelessconnectivity. For example, the peripherals 138 may include anaccelerometer, an e-compass, a satellite transceiver, a digital camera(for photographs or video), a universal serial bus (USB) port, avibration device, a television transceiver, a hands free headset, aBluetooth® module, a frequency modulated (FM) radio unit, a digitalmusic player, a media player, a video game player module, an Internetbrowser, and the like.

Although features and elements may be described above in particularcombinations or orders, one of ordinary skill in the art will appreciatethat each feature or element can be used alone or in any combinationwith the other features and elements. In addition, the methods describedherein may be implemented in a computer program, software, or firmwareincorporated in a computer-readable medium for execution by a computeror processor. Examples of computer-readable media include electronicsignals (transmitted over wired or wireless connections) andcomputer-readable storage media. Examples of computer-readable storagemedia include, but are not limited to, a read only memory (ROM), arandom access memory (RAM), a register, cache memory, semiconductormemory devices, magnetic media such as internal hard disks and removabledisks, magneto-optical media, and optical media such as CD-ROM disks,and digital versatile disks (DVDs). A processor in association withsoftware may be used to implement a radio frequency transceiver for usein a WTRU, UE, terminal, base station, RNC, or any host computer.

1.-16. (canceled)
 17. A station (STA) configured for multi-usermultiple-input multiple-output (MU-MIMO) communications, the STAcomprising: a processor; transmitter circuitry configured to transmit aMU-MIMO setup frame to a group of responder STAs comprising at least afirst responder STA and a second responder STA, for configuring thegroup to receive MU-MIMO transmissions from the STA, wherein the setupframe indicates a first antenna allocation for MU-MIMO transmissionsfrom the STA to the first responder STA and a second antenna allocationfor MU-MIMO transmissions from the STA to the second responder STA,wherein the first antenna allocation is different from the secondantenna allocation; the transmitter circuitry configured to transmitfirst MU-MIMO transmissions to the first responder STA based on thefirst antenna allocation and second MU-MIMO transmissions to the secondresponder STA based on the second antenna allocation; and receivercircuitry configured to receive a response frame from the firstresponder STA in response to the first MU-MIMO transmissions and aresponse frame from the second responder STA in response to the secondMU-MIMO transmissions.
 18. The STA of claim 17, wherein the firstantenna allocation comprises a first set of radio frequency (RF) chains,and the second antenna allocation comprises a second set of RF chains.19. The STA of claim 17, wherein the first antenna allocation comprisesa first set of virtual antennas, and the second antenna allocationcomprises a second set of virtual antennas.
 20. The STA of claim 17,wherein a first number of spatial streams comprising the first MU-MIMOtransmissions is different from a second number of spatial streamscomprising the second MU-MIMO transmissions.
 21. The STA of claim 17,wherein the MU-MIMO setup frame comprises an enhanced directionalmulti-gigabit (EDMG) MU-MIMO setup frame.
 22. The STA of claim 17,wherein the MU-MIMO setup frame comprises a medium access control (MAC)frame.
 23. The STA of claim 17, wherein the STA comprises an accesspoint (AP).
 24. The STA of claim 17, further configured to transmit anend frame to a responder STA of the group.
 25. The STA of claim 17,further configured to transmit an end frame to a responder STA of thegroup on a condition that the STA does not receive a response frame fromthe responder STA of the group in response to MU-MIMO transmissions. 26.The STA of claim 17, wherein the group comprises a third responder STA;and the MU-MIMO setup frame indicates a third antenna allocation forMIMO transmissions from the STA to the third responder STA, wherein thethird antenna allocation is different from the first antenna allocation,the second antenna allocation, or both the first and the second antennaallocation.
 27. A method for multi-user multiple-input multiple-output(MU-MIMO) communications implemented in a station (STA), the methodcomprising: transmitting, by transmitter circuitry of the STA, a MU-MIMOsetup frame to a group of responder STAs comprising at least a firstresponder STA and a second responder STA, for configuring the group toreceive MU-MIMO transmissions from the STA, wherein the setup frameindicates a first antenna allocation for MU-MIMO transmissions from theSTA to the first responder STA and a second antenna allocation forMU-MIMO transmissions from the STA to the second responder STA, whereinthe first antenna allocation is different from the second antennaallocation; transmitting, by the transmitter circuitry, first MU-MIMOtransmissions to the first responder STA based on the first antennaallocation and second MU-MIMO transmissions to the second responder STAbased on the second antenna allocation; and receiving, by receivercircuitry of the STA, a response frame from the first responder STA inresponse to the first MU-MIMO transmissions and a response frame fromthe second responder STA in response to the second MU-MIMOtransmissions.
 28. The method of claim 27, wherein the first antennaallocation comprises a first set of radio frequency (RF) chains, and thesecond antenna allocation comprises a second set of RF chains.
 29. Themethod of claim 27, wherein the first antenna allocation comprises afirst set of virtual antennas, and the second antenna allocationcomprises a second set of virtual antennas.
 30. The method of claim 27,wherein a first number of spatial streams comprising the first MU-MIMOtransmissions is different from a second number of spatial streamscomprising the second MU-MIMO transmissions.
 31. The method of claim 27,wherein the MU-MIMO setup frame comprises an enhanced directionalmulti-gigabit (EDMG) MU-MIMO setup frame.
 32. The method of claim 27,wherein the MU-MIMO setup frame comprises a medium access control (MAC)frame.
 33. The method of claim 27, wherein the STA comprises an accesspoint (AP).
 34. The method of claim 27, further comprising transmittingan end frame to a responder STA of the group.
 35. The method of claim27, further comprising transmitting an end frame to a responder STA ofthe group on a condition that the STA does not receive a response framefrom the responder STA of the group in response to MU-MIMOtransmissions.
 36. The method of claim 27, wherein the group comprises athird responder STA; and the MU-MIMO setup frame indicates a thirdantenna allocation for MIMO transmissions from the STA to the thirdresponder STA, wherein the third antenna allocation is different fromthe first antenna allocation, the second antenna allocation, or both thefirst and the second antenna allocation.